Added new function to create a compose repo file

Requires the BASE_URL be passed in the command.

Example
```
$ BASE_URL=http://something.testurl.com fab -H satqe-collab.usersys.redhat.com -u root -p ***** generate_compose_repofile
$ cat compose.repo
[sat-upgrade]
name=sat-upgrade
baseurl=http://something.testurl.com
enabled=1
```
Adresses #72 
Instead of echoing the string I would create a memory file using StringIO and then upload it to the server.

For further reference check https://github.com/SatelliteQE/automation-tools/blob/master/automation_tools/__init__.py#L619