Added 'aliases' to more entities in VALID_INCLUDES

The MusicBrainz API now supports *aliases* as a *inc=* argument for lookups: http://musicbrainz.org/doc/Development/XML_Web_Service/Version_2#Misc_inc.3D_arguments

This patch adds support for that to VALID_INCLUDES for the following entity types:

**recording**
example: http://musicbrainz.org/ws/2/recording/e87e51c3-2123-448b-8644-885756cfa28f?inc=artists+aliases

**release-group**
example: http://musicbrainz.org/ws/2/release-group/bdaeec2d-94f1-46b5-91f3-340ec6939c66?inc=artists+aliases

**release**
example: http://musicbrainz.org/ws/2/release/a6286a41-5b4f-47d4-825f-a52fac1d343f?inc=artists+aliases+artist-credits+labels

*aliases* is only valid when used with *artist*, *label*, or *work* entities (or includes), however it is ignored when they are not present, example: http://musicbrainz.org/ws/2/recording/e87e51c3-2123-448b-8644-885756cfa28f?inc=aliases