ADDITION: TVHeadend

[YurNaybor]

What this PR does / why we need it:

This PR adds TVHeadend as an installable service via Ansible and Docker. TVHeadend is a streaming and recording server for television broadcasting and can be used with different backends, like IPTV, DVB tuner cards and so on.

Which issue (if any) this PR fixes:

#325

Any other useful info:

Though I think the PR is ready as it is (and tested locally), there are still some thoughts I have:

• I added a new directory / share for recordings, because I think the "tv" folder does not quite fit the needs of TVHeadend which not only records series. I'm open for other opinions here.
• DVB drivers / firmware: I wasn't sure whether to include tasks for installing DVB drivers and firmware. For my personal hardware (WinTV Quad HD), I would need, for example, the Hauppauge ppa and the Linux media tree (see https://hauppauge.com/pages/support/support_linux.html#ppa). As this is very specific to the users hardware, I currently see this out of scope for ansible-nas.

[Vinibo]

I went on and tested it on my 'test' server. I don't know what caused it but when I complete the 'Quick setup', I end up locked out of the TVHeadend interface with a password prompt. I tried the 'admin' and 'user' password specified during the quick setup but nothing seems to work.

Here's my configuration:

tvheadend_enabled: true
tvheadend_network_mode: host

I had to put 'tvheadend_network_mode: host' for the discovery of my HDHomeRun.

[davestephens]

Closing due to no activity, and I don't have the hardware to test it.