updating dependencies.

Basically, I was updating the dependencies on brahmin and saw some warnings on purnam.native

WARNING: Bad method signature in protocol implementation ICollection -conj at line 126 file:/Users/pasviegas/.m2/repository/im/chit/purnam.native/0.4.3/purnam.native-0.4.3.jar!/purnam/native.cljs

So I guess this fixes that.

- Added lein-ancient plugin to detect outdated dependencies
- Updated dependencies
- Removed warning while extending ICollection -conj.