Added verbose logging to sync_folder_to_container #250

Added the ability to specify a prefix to be added to the object name during checking and uploading during a sync

Sped up sync_folder_to_container by having it pull down a list of objects all at once to use to compare against instead of checking once for each file.
Fixed code formating.
Changed the prefix parameter to object_prefix to not get confused with the existing prarameter called prefix which I restored.

Changed to use the python logging method instead of using print statements.

Renamed log_level to verbose and changed it to a simple boolean variable.
Merge branch 'sync_improvements' of github.com:mlilius/pyrax into mlilius-sync_improvements
Removed extra newlines.