plovr now compiles with Buck!

On my machine, a clean build of `buck build plovr` takes 11.3 seconds
whereas `ant jar` takes 19.5 seconds.

I expect that the improvement in incremental build times using Buck vs.
Ant to be even more significant.
Got most tests passing with `buck test --all`.

Failures:
FAIL org.plovr.NameCollisionTest
FAIL org.plovr.ManifestTest

These are failing because I have not migrated all of the
resource-packaging logic over from Ant to Buck.
Tried to get the .properties files in the right place.

Unfortunately, I'm not sure Buck has the ability to put
these in the desired place in the JAR quite yet.
Add .nobuckcheck to .gitignore.
Replace `junit.framework.Assert` with `org.junit.Assert`.

This is in preparation for upgrading to JUnit 4.11.
Upgrade JUnit 4.8.2 to 4.11.
Upgrade from Guava 14.0.1 to Guava 15.0.
Adapt the plovr error reporter for normal input files,
so that we get errors when compiling soy in RAW mode.
Put goog.requires in HTML, so that symbols are loaded in the right order