Update start.rst

changed the line for the requirements install command from working on requirements/base.txt to requirements.txt
adding postgresql-devel for fedora installation

this is a solution for not finding libpq-fe when compiling.
Merge pull request #12 from moshe742/patch-1

Update start.rst - replaced requirements/base.txt with requirements.txt
Merge pull request #13 from moshe742/patch-2

adding postgresql-devel for fedora installation
Fixed importer issues caused by idle generic relations using uuidfield to referencesource and auxsource
Initial implementation of cleanup() - currently used for deleting new sheet's template that's not different