Ability to pull more than one sheets in one run

[bastienboutonnet]

The idea would be to have feature where you can pass a list of sheets to parse from the yml or loop through the entire sheets.yml if we want.

Down the line, tagging would also be a good idea.

[bastienboutonnet]

This will require to wait for a project/profile architecture so that it does not have to get completely rewritten again when that happens in 0.3

[bastienboutonnet]

Possibly a good idea to wrap the iteration in a parallel process to run more than one sheet at once