Make sure subset ids are filled before creating job in frequency plot.

Fixes error when running analysis the first time.
Update frequency plot analysis to use Cairo for png rendering.
:fish:
:fish:
Refactor analysis pipeline for acgh group test
Fix problems with image generation and rendering
Fix odd import
Fix variable quoting
Linking to zip in analysisFiles
Merge pull request #97 from thehyve/features/refactor_acgh_group_test

Features/refactor acgh group test
Remove unneeded dependency
Merge thehyve/master into thehyve/london_hackaton
Merge thehyve/london_hackaton into transmart/london_hackaton