Update ubuntu

- `ubuntu:precise`: 20150228.11
- `ubuntu:trusty`: 20150228.11
- `ubuntu:utopic`: 20150228.11
- `ubuntu:vivid`: 20150309

library/ubuntu

@@ -4,31 +4,31 @@
 # see also https://wiki.ubuntu.com/Releases#Current
 
 # commits: (master..dist)
-#  - 50d175c Update tarballs
-#    - `ubuntu:precise`: 20150212
-#    - `ubuntu:trusty`: 20150218.1
-#    - `ubuntu:utopic`: 20150211
-#    - `ubuntu:vivid`: 20150218
+#  - d0f6462 Update tarballs
+#    - `ubuntu:precise`: 20150228.11
+#    - `ubuntu:trusty`: 20150228.11
+#    - `ubuntu:utopic`: 20150228.11
+#    - `ubuntu:vivid`: 20150309
 
-# 20150212
-12.04.5: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd precise
-12.04: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd precise
-precise-20150212: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd precise
-precise: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd precise
+# 20150228.11
+12.04.5: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 precise
+12.04: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 precise
+precise-20150228.11: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 precise
+precise: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 precise
 
-# 20150218.1
-14.04.2: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd trusty
-14.04: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd trusty
-trusty-20150218.1: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd trusty
-trusty: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd trusty
-latest: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd trusty
+# 20150228.11
+14.04.2: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 trusty
+14.04: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 trusty
+trusty-20150228.11: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 trusty
+trusty: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 trusty
+latest: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 trusty
 
-# 20150211
-14.10: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd utopic
-utopic-20150211: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd utopic
-utopic: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd utopic
+# 20150228.11
+14.10: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 utopic
+utopic-20150228.11: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 utopic
+utopic: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 utopic
 
-# 20150218
-15.04: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd vivid
-vivid-20150218: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd vivid
-vivid: git://github.com/tianon/docker-brew-ubuntu-core@50d175ca0b2820fcdb213455d46d1a47f11493cd vivid
+# 20150309
+15.04: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 vivid
+vivid-20150309: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 vivid
+vivid: git://github.com/tianon/docker-brew-ubuntu-core@d0f6462dc68f2719836c3c29bc5551b34140b1e2 vivid