[TW-60] Allow auto-complete for constrained string-type UDA values

_David Patrick on 2014-01-21T18:44:23Z says:_

Perhaps a cryptic subject line, this feature is to suggest a connection between a set of constrained string-type UDA values, and the ability to then use a partial string, to enter one of those values.

To clarify, let's say I made a uda called "belt" whose values were colors

uda.belt.type=string
uda.belt.values=white,yellow,orange,green,purple,black,rope

having constrained those values, I should be able to now use any non-ambiguous part, as short-hand.

$ tw add learn about custom reports belt:o

(recorded as belt:orange) and then

$ tw b:o

make sense?