Clean up BindDatabaseCommand and AutoMediaAssignerCommand.

No functional changes. Just restructuring code to be more efficient or
cleaner.
Rename AutoMediaAssignerCommand to AssignMediaCommand.
Reorganize bundle and database commands into separate namespaces.
Create UpdateControlTextCommand for binding databases.
Create CreateSpecialPropertiesCommand for binding database.
Remove non-Field backed properties from Media rows.

Media and WixMedia rows contained properties that were set during
binding but not backed by Fields and thus not persisted to the .wixpdb.
That is not a desirable pattern so remove them and fix the code. Also,
extracted ProcessUncompressedFiles into a command.
Merge pull request #55 from robmen/binder-database-refactor

Binder database refactor