added cacheing package

configured settings files
added decorations in urls.py

todo:
adjust cacheing levels to something that makes sense
not totally sure which pages should be cached in the first place (obviously static pages, but should there be any level of cacheing on more frequently accessed pages like my_links?)
not sure how to test outside docker or whether settings.py.template is correct (roomlist copypaste)

this is not a final commit
4 jobs for 39-pagecacheing in 1 minute and 3 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #1664
Go-py2.7

00:00:48

passed #1665
Go-py3.4

00:01:03

passed #1666
Go-py3.5

00:01:03

passed #1667
Go-py3.6

00:01:03

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