Add ``shell`` parameter for shell.
Add ``shell`` parameter for shell.

We can use glob in command by setting shell to True:

    shell('ls *.html', output='result.txt', cwd='./pages', shell=True)

drayanaindra/python-livereload,mgedmin/python-livereload,lepture/python-livereload,blueyed/python-livereload,blueyed/python-livereload,mgedmin/python-livereload,TheLady/python-livereload,tjwalch/python-livereload,blueyed/python-livereload,tjwalch/python-livereload,lepture/python-livereload,drayanaindra/python-livereload,marble/python-livereload,marble/python-livereload,TheLady/python-livereload,mgedmin/python-livereload