Make uniquelist work both as module and a script

[llimeht]

The details of __builtin__, __builtins__ and builtins differ according to whether it's a script of a module and between Python 2 and 3. This PR regularises uniquelist to work in all these situations.

Notes:

• this function appears to be unused in any case; perhaps just remove the file instead?
• avoiding using the names of builtins such as hash as variables (and list which is (ab)used extensively in sasview) would avoid this too

(BTW I discovered this bug because py.test accidentally picked up the file and ran the test and it failed)

[pkienzle]

Since uniquelist is not referenced anywhere in sasview, just get rid of it instead of adding 2-vs-3 cruft.