Added StandardDeviationKeyVal operator and test class.
SPOI-1182 -

Added the Filter operator that can filter the key-value pairs based on the given filter. The keys in the KeyValuePair has to be implement a Filterable interface.

Also added required test cases.
Merge branch 'SPOI-1182'
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' of https://github.com/DataTorrent/Malhar
Merge branch 'master' of https://github.com/DataTorrent/Malhar
#MLHR-835 #comment Fixed the file path issue, read the sample text file from the classpath.
#MLHR-835 #comment Added duration for the test case.
#MLHR-835 #comment Also fixed an issue with Twitter Rolling Top Words application. Most of the code was commented.
#MLHR-835 #comment Added log file and sample text file for Map-Reduce applications.
Merge branch 'master' of https://github.com/DataTorrent/Malhar
#MLHR-872 #comment Added demo guides for Twitter Top URL Counter, Twitter Rolling Top Words and Word Count Apps.
#MLHR-835 #comment Changes to move the stream.close calls into finally block.
Merge branch 'master' into my_master
moved the codec to codec package
Minor.
Relocate codec classes to codec package.

Conflicts:
	apps/src/main/java/com/datatorrent/apps/logstream/DimensionOperator.java
	apps/src/main/java/com/datatorrent/apps/logstream/LogstreamTopN.java
MLHR-936: added lettuce store and fixed a bug in redis store
Merge pull request #820 from chandnisingh/MLHR-936

MLHR-936: added lettuce store and fixed a bug in redis store
Merge branch 'MLHR-872_pull' of https://github.com/atuldambalkar/Malhar