moved context activities to its own section

Further explanation of 'parent', 'grouping' and 'other' to be added. 
changes to context activities

these will need some discussion
changed URI to URL

Because the requirement to make a human-readable description at 
a URI only makes sense for URIs which are URLs. 
Changed format of endpoint examples
various minor amends
Merge pull request #5 from garemoko/workingCopy

Merging changes to 'Working copy' into 'master' ahead of tomorrow's meeting