Complete PomdpXWriter Class with tests
improved doc-strings
removed unnecessary comments
Merge branch 'writerClass' of https://github.com/jp111/pgmpy into jp111
Merge branch 'jp111' into dev
added indent method for prettyprint formatting similar to ProbModelXML
Merge branch 'writerClass' of https://github.com/jp111/pgmpy into jp111
Merge branch 'jp111' into dev
Merge remote-tracking branch 'upstream/dev' into dev