Add GDS Verify module changes

__* PR #31 was originally opened to merge GDS Verify changes in to this module. After some comments, I thought it best to close PR #31 and create a new branch with cherry picked changes. Hopefully this should be a bit clearer than one big commit (as is the case in the original PR) *__

GDS Verify(IDA) project use a fork of this graphite module. It seems like a good idea to incorporate changes in to this module, with the view the Verify project dropping the fork and using only this module.

The GDS Verify additional changes are:

Ability to specify the user used to run the processes
Install from Debian package
Some carbon cache options
This was introduced in 63e8da1 and it doesn't explain the hasrestart change. The two instances of `hasrestart` below were changed in 5df15dd which has an explanation. Would it be possible to amend 63e8da1 to give a description (like in 5df15dd) of why `hasrestart` needs to change?