[connectionagent] Add option to keep tech powered when disabling tethering.

It is sometimes desirable to not restore the power state of the
tethering technology. Add an option to allow the caller to request that
the tethering technology stays powered when disabling tethering.

Removed generated file from repository and generate it at build time.
Merge pull request #79 from amccarthy/master

[connectionagent] Add option to keep tech powered when disabling tethering.