config: cleanup and reorganized

refs #36
docs-config: initial info

refs #36
docs: flask secret key

refs #36
fixes #46
config: secrets needed

refs #36 #46
Merge pull request #44 from orvsd/docs_config

Config documentation
refs #36 #46
Made install_course_to_site more configurable
Corrected github issue #2 by moving variable values to config/default.py.dist
Corrected default.py.dist var assignment : to =
added INSTALL_COURSE_ before new var names
refs #2 put config keys in 'quotation marks'
install_course: fix rebase fail

refs #2