SQLite Output

[fabianhauser]

This Pull Request implements a sqlite output. It basically creates the tables according to the scheme, and additionally:

• extracts milestones into a milestones table
• extracts labels into a labels table, and linked to issues / merge requests using label_groups
• creates statistics as VIEWs (view_time_per_user and view_time_stats)

[coveralls]

Coverage remained the same at 65.979% when pulling 387ba7d on fabianhauser:sqlite-output into e059f1f on kriskbx:master.