Remove library eviction warnings with sbt

[pankajgupta]

When using sbt, we are currently getting:

[warn] There may be incompatibilities among your library dependencies.
[warn] Here are some of the libraries that were evicted:
[warn] * com.google.guava:guava:13.0.1 -> 16.0.1
[warn] Run 'evicted' to see detailed eviction warnings

[szymonm]

The problem is "com.github.spullara.mustache.java" % "compiler" % mustacheVersion dependency of twitter-server that needs guava 13.0.1.

And twitter-utils depends on com.google.code.findbugs:jsr305:1.3.9 that is also old.

@travisbrown @caniszczyk Can you do anything about that?

[pankajgupta]

At least twitter-server should not be needed in cassovary-core. I have removed it (in commit d6032e6) as a shared dependency and left it for only cassovary-server (for which the eviction problem remains).