exit with help if no subcommand is supplied.
Default to verbose output on cli. added size-hint option. increased chunk_size.
Merge branch 'master' of github.com:jjjake/ia-wrapper into refactor

Conflicts:
	internetarchive/iacli/ia.py
	internetarchive/iacli/ia_upload.py
Added `get_session()` function.
Updated `Item` docstring.
use `get_session()` to establish session.
cleaning up `get_files()`.