singular versions of get methods

[rsgalloway]

all "get" methods are plural currently:

>>> sg.get_projects("Demo: Animation")[0].get_sequences("080")[0].get_shots()
[<Shot "bunny_080_0100">, <Shot "bunny_080_0200">, <Shot "bunny_080_0300">]

it might be good to have singular versions of these:

>>> sg.get_project("Demo: Animation").get_sequence("080").get_shots()
[<Shot "bunny_080_0100">, <Shot "bunny_080_0200">, <Shot "bunny_080_0300">]