Remove vendored copy of fbjni (#530)

Summary:
Pull Request resolved: https://github.com/facebook/flipper/pull/530

Use the pre-release of fbjni instead of our bundled copy. I hope this can be made a little less awkward, but it works for now.

Reviewed By: jknoxville

Differential Revision: D16988077

fbshipit-source-id: 936e414f9b2bf82ccb54b107228d79d01acdbf14

settings.gradle

@@ -6,7 +6,6 @@
 
 include ':android'
 include ':folly'
-include ':fbjni'
 include ':easywsclient'
 include ':sonarcpp'
 include ':sample'
@@ -18,7 +17,6 @@ include ':rsocket'
 include ':third-party'
 include ':noop'
 
-project(':fbjni').projectDir = file('libs/fbjni')
 project(':easywsclient').projectDir = file('libs/easywsclient')
 project(':sonarcpp').projectDir = file('xplat')
 project(':sample').projectDir = file('android/sample')