Fix Travis maven build to download from central
Re-add quiet for mvn install, things look better
Create CONTRIBUTING.md, copied from Truth's.
Add java8 to travis.
Fix last flaky test (that I know of).  The problem was we were asserting that something existed in a child injector (through inference, by checking it was in the parent blacklist), but if GC ran it could have been ejected from the parent blacklist (since the child injector isn't strongly referenced anywhere).

There's an actual problem here that we should fix (remove items from the parent blacklist immediately if the child injector fails to create itself), but before fixing that we can at least make the test not flake.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71369181
Fix issue 597 -- entity manager is properly removed even if close operation fails + unit test.
Fix issue 597 -- JUnit 3 style
Fix issue 597 -- Adds copyright header.
Cleanup javadocs.  This makes the following changes:
  1) Stop using doclava.  It has too many bugs (like dropping annotations).
  2) Tell javadoc not to doclint.  Java8 does it and errs if it fails.
  3) Link to appropriate third parties from javadoc.
  4) Split extensions into separate groups in ant javadoc.
  5) Cleanup code that had javadoc warnings.
Publish javadocs using jdk8, not jdk7.