Campaign Manager 1.2

Changes and improvements since Campaign Manager 1.1:

#33 Basic activities reporting to campaign screen - by @scardinius, @systopia
#44 Add settings for built-in KPIs - by @systopia
#47 Clean up action links in campaign view - by @systopia
#45 Cache KPIs - by @systopia
#55 To edit previously added expense you need to click through all of the expense fields - by @kpomaranska, @systopia
#46 Load KPIs asynchronously - by @kpomaranska, @systopia
#43 Show custom groups in campaign view - by @scardinius, @kpomaranska, @systopia
#48 When adding parent to the campaign, it external id is set to null and this is visible on the campaign dashboard - by @kpomaranska, @systopia
#36 alpha 1.1: detail page empty - by @bkaless, @scardinius, @jaapjansma
#61 Installation fails due to method from config class - by @scardinius
#63 View page not loading when there aren't any custom groups for campaigns - by @scardinius
#74 Provide German localisation - by @jensschuppe
#72 "Delete" action link for campaigns not working - by @scardinius, @jensschuppe
#66 Missing permission for CampaignTree API - by @scardinius
#80 Migrate documentation to MKDocs - by @jensschuppe
#69 Get expences without limitation to first 25 records - by @scardinius
#82 Fix parent campaign order being reversed in campaign view - by @pfigel
#86 Improve displaying custom fields on the campaign dashboard - by @jensschuppe