Move convenient path selections in push/pull

[MischaPanch]

We should make it easier to push/pull a bunch of paths based on patterns. For that we should add

• Permit passing glob-patterns to push
• Permit passing glob-patterns to pull
• Add the possibility to pass a regex as except_matches kwarg to permit simple exclusion of files. The current regex kwarg should be renamed to if_matches.

This would permit things like

storage.push("data/**/*.jpg", except_matches=r".*test.*") 

We could additionally allow passing a except_condition: Callable[[str]], bool] = None (or do you think if_condition is more natural?), in which case the above can be rewritten

storage.push("data/**/*.jpg", except_condition=lambda n: "test" in n) 

The condition could be even made more general, mapping the metadata-object to a bool (thereby e.g. allowing filtering by size), at the cost of a more complicated interface for callables. @fariedabuzaid @AnesBenmerzoug what do you think?

[MischaPanch]

Condition is not really needed for now, can be added later. Since the transaction is based on summaries, the condition could be more involved (e.g. including file size and other things). Passing globs to push was implemented, as well as exclude_pattern. Passing glob to pull was not implemented and might not be needed, it is a bit more complicated to do

[MischaPanch]

Closing this, libcloud does not support glob-patterns for listing and implementing this by ourselves would be messy