Add ignored_types option to CapitalizationInSelector

Add new `ignored_types` option to `CapitalizationInSelector` linter,
which allows you to selectively ignore capitalization in certain types
of selectors.

This is useful when you using a different naming convention for an
entire type of selector (e.g. you allow camel casing attributes, for
some reason).

Change-Id: I6868256dfcfa6e5260dfe422fb78b84b0a825e4e
Reviewed-on: http://gerrit.causes.com/40965
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane.dasilva@brigade.com>