(bug 46153) Subject namespace to thwikibooks, change wgSitename

This commit does two things:
* (1) Adds 102 and 103 ('Subject' and 'Subject_talk') namespaces
to thwikibooks, with their appropriate Thai names, as requested.
* (2) Changes wgSitename into 'วิกิตำรา'.

Change-Id: Ic0fd7aee1e35b07f5e907f53bb303414c622b8f7