[bfss] convert root BFSS directory to str in constructor (closes #2137793)
otherwise you can get crashed with AssertionError: Binary objects must use raw strings, not <type 'unicode'>
\.svn
^build$
^dist$
\.pyc$
\.pyo$
\.bak$
\.old$
\~$
\#.*?\#$
\.swp$
^doc/book/en/apidoc$
\.old$
syntax: regexp
.*/data/database/.*\.sqlite
.*/data/database/.*\.config
.*/data/database/tmpdb.*
^doc/html/
^doc/doctrees/
^doc/book/en/devweb/js_api/