POM.xml updated

- comments for dependency description added.
- junit updated. (4.11)
- hamcrest updated. (1.3)
- junit & hamcrest's dependency conflict resolved.
- mahout & guava's dependency conflict resolved.
POM.xml updated

- apache commons-lang3 for language extension added.
assembly plugin configured
maven compiler plugin: 3.0 -> 3.1
dependency reconfigured: hadoop, mahout, guava, apache commons, slf4j