small improvment of doc
now supporting custom http headers
changed bootstrap to keep-on with buildout 1 for the moment
indicate that buildout is mainly for tests not regular use
added z3c.rml as a dependency for tests
fixed unoconv tests to account for the fact that file is not necessarily deleted anymore (see c7d8bb55)
fixed a small bug in unoconv_worker, when dest_fmt is empty
adde test_http_headers for http worker, and removed a pdb \!