add build dependency for el5 and new functional tests

* asciidoc indirectly requires docbook-style-xsl on el6 and f20,
  but not on el5. Resolve failure to build tito with tito on el5:
  "I/O error : Attempt to load network entity"

* Resolve "egg missing file" on el5 due to busted symlinks
  from 20c4f1b7c0942.

* Add functional test to build tito with itself in order to
  catch problems like the ones above.

Closes https://github.com/dgoodwin/tito/issues/133