[NUTCH][MEMEX] port the Generator Module (aka scoring plugin )

[thammegowda]

Sub tasks:

• Define Scoring plugin interface
• Port over Cosine Similarity from Nutch to Sparkler
• Port over Naive Bayes Filter from Nutch to Sparkler
• Integrate Domain Explorer code into this generation module

CC @sujen1412

[thammegowda]

Progress: the Scoring interface is defined. We are yet to port nutch plugins