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.
new http lines input operator
fix #MLHR-928
moved from stram to dt
fixed test case
Merge pull request #817 from gauravgopi123/MLHR-928

fix #MLHR-928
Merge pull request #816 from davidyan-malhar/httpLinesInputOperator

Http lines input operator
Merge branch 'master' into my_master