allow callers to specify their own Handler
Merge pull request #231 from mlc/custom_handler

Introduce DisplayImageOptions.handler()
Java docs
Issue #229 - ConcurrentModificationException
Issue #234 - NPE in LimitedDiscCache
Travis CI support
Issue #189 - Add Unit Tests
Built new snapshot
Readme: added apps, Flattr
Clean imports
Update Readme
Issue #233 - NPE in LruMemoryCache if pre-processor returns null
Refactored LOG constants
Fixed Readme
Built new snapshot
Issue #244 - Low performance of MemoryCacheUtil.generateKey
Optimized String work (avoid String.format(...))
Optimized methods with var-args