author: Mia Schambeck
summary: fix pull; move more code to functions; implement remote receive hook
- Fix pull
The checks for send and pull were previously the same, which is
problematic since they expect different states for the repo.
For pull it is expected to receive a remote repo with more commits
and/or files.

- Move code to functions
Some more parts of the send/pull are now split out to functions (shell
has function arguments weee).

- Remote receive hook
If the file `.sortle/remote-run-after-send` exists, sortle tries to run
it after calling `sortle send` using ssh.
