Podcast management

[jfenske89]

• Added support for retrieving and storing user roles (permissions).
• Added podcast management support (adding and deleting podcasts)

Demo:

• Desktop: https://www.dropbox.com/s/8o322n6ia5wa69w/airsonic-refix-podcast-management-desktop.mov?dl=0
• Mobile: https://www.dropbox.com/s/kwppn5hk30gcn9m/airsonic-refix-podcast-management-mobile.MP4?dl=0

[tamland]

This is supported now. Implemented in a different way