Column family support in RocksJava

This commit includes the support for the following functionalities:
  - Single Get/Put operations
  - WriteBatch operations
  - Single iterator functionality
  - Open database with column families
  - Open database with column families Read/Only
  - Create column family
  - Drop column family
  - Properties of column families
  - Listing of column families
  - Fully backwards comptabile implementation
  - Multi Iterator support
  - MultiGet
  - KeyMayExist
  - Option to create missing column families on open

In addition there is are two new Tests:
- Test of ColumnFamily functionality
- Test of Read only feature to open subsets of column families
- Basic test to test the KeyMayExist feature

What is not supported currently using RocksJava:
- Custom ColumnFamilyOptions

I decided to file a pull request w/o the missing two features to omit
some merging trouble.

The following targets work as expected:
  - make rocksdbjava
  - make jtest

Test environment: Ubuntu 14.04(LTS, x64), Java 1.7.0_65(OpenJDK IcedTea 2.5.2), g++ 4.8.2, kernel 3.13.0-35-generix