Added -d flag for debug output. Turns out there is a bug in tm.plugins.sentiment

Error in slam:::`[.simple_triplet_matrix`(x, i, j, ...) :
	  NA indices not allowed.
Added exclusion for .RData files
Better detection of R install. --r-dir command-line option.
Merge branch 'master' of github-mkfs:mkfs/sentiment-analysis