Bump requests from 2.9.1 to 2.18.4
Bump requests from 2.9.1 to 2.18.4

Bumps [requests](https://github.com/requests/requests) from 2.9.1 to 2.18.4.
- [Changelog](https://github.com/requests/requests/blob/master/HISTORY.rst)
- [Commits](https://github.com/requests/requests/compare/v2.9.1...v2.18.4)
edx/configuration,gsehub/configuration,gsehub/configuration,arbrandes/edx-configuration,Stanford-Online/configuration,mitodl/configuration,EDUlib/configuration,appsembler/configuration,gsehub/configuration,mitodl/configuration,stvstnfrd/configuration,hks-epod/configuration,arbrandes/edx-configuration,stvstnfrd/configuration,Stanford-Online/configuration,Stanford-Online/configuration,rue89-tech/configuration,appsembler/configuration,EDUlib/configuration,hks-epod/configuration,appsembler/configuration,arbrandes/edx-configuration,edx/configuration,hks-epod/configuration,stvstnfrd/configuration,rue89-tech/configuration,stvstnfrd/configuration,edx/configuration,mitodl/configuration,stvstnfrd/configuration,arbrandes/edx-configuration,Stanford-Online/configuration,hks-epod/configuration,rue89-tech/configuration,gsehub/configuration,arbrandes/edx-configuration,appsembler/configuration,EDUlib/configuration,Stanford-Online/configuration,gsehub/configuration,mitodl/configuration,hks-epod/configuration,rue89-tech/configuration,rue89-tech/configuration,edx/configuration,EDUlib/configuration,EDUlib/configuration