t: remote-hg: add file operation tests

Inspired by gitifyhg.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
t: remote-hg: trivial cleanups and fixes

There was a broken && chain, and cat is simpler than echo in a subshell.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
remote-hg: add support for hg v3.0

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
travis: add specific test for hg v3.0

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>