argsparser.py: Adds --storage cli option
Adds initial files for layman sync plugin
layman_.py: Adds subprocess use of --storage flag

In order to respect the location of the repository defined by repos.conf
the subprocess now specifies the storage location.
layman_.py: Overrides default storage value for API

The default storage value will be overwritten upon initialization
of the LaymanAPI in order to respect the location reported by
repos.conf. Checks have also been added to ensure the location being
reported by the LaymanAPI is the actual location of the repository
reported by the repos.conf file. If it is not, then the LaymanAPI
will be re-initialized with the new storage location.
reposconf.py: Adds sync-type checking