Add networking timeouts to git pushes

[hannesg]

The solution take is highly unelegant but kinda unavoidable given the options available. Basically, libgit as most c based libs doesn't allow cancelling anything. The only thing we can do is to run the push operation in a seperate go routine and return our own timeout after some time while throwing a cancellation at the lib to stop. This is now done in the useRemote function. The network timeout is now 1 minute which is probably good enough for most consumers.