Fetch Tautulli straight from git master and add python-pip from entware

[stefaang]

Installation was failing when fetching pip with get-pip.py.

• use entware python-pip package instead of get-pip
• added sanity checks during install
• restore db and config on install (only applies to installs after this version)
• add entware as installation dependency
• use git to fetch tautulli instead of downloading a package