Support fetch with full url

[dimabru]

Describe the solution you'd like
We need to be able to support fetching with full url (instead of just owner/repo)
For example:
allero fetch https://github.com/allero-io/allero
allero fetch https://github.com/allero-io

[jmj0502]

This seems like a cool enhancement. Would like to give a shot if it gets approved c:

[dimabru]

hey @jmj0502
Thanks a lot for offering to take this issue!
I've already started working on it but may I suggest you take #78?

Also, once I'm done with this issue you can take #94 if you'd like :)