Added migration guide from version 0.2.9
Updated README.md documentation
* splitter DeepSparkContext into CassandraDeepSparkContext and MongoDeepSparkContext
* renamed DeepJobConfigFactory to ConfigFactory
Merge branch 'deep-refactor-different' of github.com:Stratio/stratio-deep into deep-refactor-different

# By rcrespodelosreyes
# Via rcrespodelosreyes
* 'deep-refactor-different' of github.com:Stratio/stratio-deep:
  have been erased unnecessary files
  added: now it throws an exception instead of returning null

Conflicts:
	deep-commons/src/main/java/com/stratio/deep/context/DeepSparkContext.java
	deep-mongodb/src/test/java/com/stratio/deep/config/GenericConfigFactoryMongoDBTest.java
	deep-mongodb/src/test/java/com/stratio/deep/rdd/mongodb/MongoEntityRDDTest.java
Merged previous refactors with mongo's test changes