Add reload support to chan_skinny.

Special thanks goes to DEA who had to redo this patch twice
because we first put unload/load support in and later redid the way
we configure devices and lines.

(closes issue #10297)
Reported by: DEA
Patches:
      skinny-reload-trunkv2.diff uploaded by wedhorn (license 30)
      skinny-reload-trunk-v4.txt uploaded by DEA (license 3)
	  With mods by me based on feedback from wedhorn and Russell and seanbright
Tested by: DEA, mvanbaak, pj

Review: http://reviewboard.digium.com/r/130/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@179122 65c4cc65-6c06-0410-ace0-fbb531ad65f3