setup: bump WebOb to >=1.7 TurboGears will soon require WebOb>=1.7 and that cause an innocent test change. Older WebOb versions also required older WebTest versions but the WebTest dependency from Pylons will now automatically pick compatible versions.

# requirements.txt file for use as "pip install -r requirements.txt" as a
# readthedocs compatible alternative to "pip install -e ." which is a working
# alternative to "setup.py develop" which doesn't work with Mercurial 3.7
.