DESeq2 adjusted p-value threshold and minor bugfixes

New features and minor bugfixes

Adjusted p-value threshold (#14)

• Users can now set an adjusted p-value threshold for plots generated from DESeq2 differential expression analysis. Default is adj. p-value <= 0.05.
• Adj. p-value now also displayed on all *-diffexpr-countplot.pdf files

Bugfixes

• knownMods table now a defaultdict(list) to prevent KeyError after 1st mapping round and subtracting predicted from known mods in unknownMods() - (#9)