Add the nemo-terminal package

This is a direct port for the nautilus-terminal package. Only
superficial renames of Nautilus -> Nemo were required.
nemo-terminal nemo-integration improvements

* Store all settings in dconf under the org.nemo.extensions.nemo-terminal key
* Add "paste filenames" support for the terminal.
* Support for terminal following Nemo to GVFS mountpoints.
  * Use GFile for converting URIs to path names.