Merge pull request #136 from Edugate/develop

speedup discojson generation by 40%
Merge branch 'develop' into 1.x-stable
Merge branch 'develop' into 1.x-stable
Merge branch 'develop' into 1.x-stable
Merge pull request #137 from Edugate/develop

arpgen speed improvement
Merge branch 'develop' into 1.x-stable
Merge branch 'develop' into 1.x-stable
fix exception for empty collections