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

🔖 Preparing release of 1.5.2

Merge branch 'staging/hotfix' into master

🔖 Preparing release of 1.5.0

🔖 Preparing release of 1.5.0rc3

🔖 Preparing release of 1.5.0rc2

➕ Python 2 needs enum34 dep

🔖 Preparing hotfix release of 1.4.2

Merge branch 'master' into staging/maintenance

🔖 Preparing release of 1.4.1rc4