Make docs build when header files change, make svnversion work properly with long file names both on msvc.  Still need to address the situation when svnversion is not found on the machine, when the internet is not available to determine version at build time, or what to do when the release is from a tarball, and not an svn checkout.

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@320 d0543943-73ff-0310-b7d9-9358b9ac24b2