Update for installation through dpkg

[owenthereal]

As mentioned in #125 (comment), the current update implementation may not work for installation through dpkg. My impression so far is there may be no solution to this since it's hard to keep track of how people install gh. Even there is, it'll significantly increase the complexity of the software. Need more investigation to this.

[calavera]

Now that we have a setting to autoupdate, maybe we could use it to indicate that you don't want to use gh to udate gh ever, something like "autoupdate": "never".

That way if you install gh using a package manager, you could set this option and then use the same package manager to update whenever you want.

[owenthereal]

Great suggestions! I'm gonna test out what it'll actually complain if I update after installation with dpkg

[owenthereal]

@calavera Should we close this one since #172 has been merged? The user could just type git --global gh.autoUpdate never to stop autoupdate.

[calavera]

I think so. Closing

[owenthereal]

Hooray! We're almost there! #145