Merged 1.3.9rc1

1.3.9.20180701

Merge tag '1.3.9rc1'

Merged 1.3.7

1.3.7.20180415

fix merge with 1.3.7

Merging stable release 1.3.5

1.3.5.20171121

allow multiple upload

Merge upstream maintenance branch

1.3.5rc3.20170918b

Merge branch 'master' of github.com:eyal0/OctoPrint

Merge v1.3.4

1.3.4.20170615

Merge remote-tracking branch 'foosel/maintenance'

Maintainence release and multiple upload

Allow uploading multiple stl at once

Maintenance release

1.3.2-20170429b

Maintenance release

Maintenance release

1.3.2-20170424

Merge remote-tracking branch 'foosel/maintenance'

Merge in 1.3.2 from upstream

sync with foosel master

Fix Octoprint to accept releases that start with a v

OctoPrint will be able to update repositories that use tags that start with a v, even on OctoPi.