Use an FDroid specific NSD service type, based on SSL preference.

NSD service types follow a DNS SRV convention _protocol._transport used in
mDNS. Previously Kerplapp was advertising an _http._tcp service
generically. It makes more sense to advertise a _fdroidrepo._tcp service so
the FDroid client can run a discovery that it knows won't return generic
non-FDroid repo HTTP servers.

Further, we should advertise _fdroidrepo._tcp when the use_ssl preference is
disabled and _fdroidrepos._tcp when it is enabled to indicate to the
discovering peer whether we are advertising an HTTP or an HTTPS FDroid repo.

refs #2467
Fixing compiler warnings, standardized exception printing.

Cleared up the low hanging compiler warnings shown in Eclipse: unused
imports, etc. The SettingsActivity will have to be addressed in later
releases as it uses some deprecated methods.

Changed all of the catch() blocks across the application to use Log.e()
instead of err.printStackTrace();
set default repo name to the BRAND/MODEL of the device

Having the default repo name be the BRAND/MODEL should make it easier to
identify the device in question without broadcasting sensitive info like
unique IDs, names, or email addresses.  Users can still easily customize
the name in the Settings.

Now that we have a more descriptive repoName, use it anywhere it makes
sense to have it.