Merge pull request #4 from pmahoney/master

Travis setup + some bugfixes
Use hacky workaround of strange bug to write bytes to output stream.
Fix creation of eager env hash.
Move to Java impl of core parts of rubylet.  Add 'large response' integration test.
Remove obsolete environment spec.
Use Block.NULL_BLOCK rather than illegal null.
Require 'rubylet' rather than old 'rubylet/servlet'; print out error test on 500 errors in tests.
Make specs depend on :compile task.
Use more direct Rack response array access; avoid ruby1.8/ruby1.9 compat assertions.
Use logback to log output of rubylet-ee tests.
Don't store reference to ASYNC_COMPLETE in constructor; fetch as needed.
Add one-pass header-to-rack method; store some common headers as constants.
Rename rubylet to rubylet-rack; rubylet-jetty to rubylet-rack-handler.
Change specs for module renames.
Remove unused imports.
Implement StaticFileFilter in java.
Move catch(:async) {} into the Java layer.
Update invocation of Bundler; remove deprecated :rubygems from Gemfile.
Update for module renames.
Add small rubylet-rack example.