Prometheus version 0.4.0.

Change-Id: I752044a69f86aacc5a7e6da62a6f4a187cf67d27

CHANGELOG.md

+## 0.4.0 / 2014-04-17
+
+* [FEATURE] Vectors and scalars may now be reversed in binary operations (`<scalar> <binop> <vector>`).
+* [FEATURE] It's possible to shutdown Prometheus via a `/-/quit` web endpoint now.
+* [BUGFIX] Fix for a deadlock race condition in the memory storage.
+* [BUGFIX] Mac OS X build fixed.
+* [BUGFIX] Built from Go 1.2.1, which has internal fixes to race conditions in garbage collection handling.
+* [ENHANCEMENT] Internal storage interface refactoring that allows building e.g. the `rule_checker` tool without LevelDB dynamic library dependencies.
+* [ENHANCEMENT] Cleanups around shutdown handling.
+* [PERFORMANCE] Preparations for better memory reuse during marshalling / unmarshalling.

VERSION

-0.3.0
+0.4.0