Merge branch 'hotfix/requirements'

Close #43
Merge branch 'security/updates-should-use-input-filter'

Ensure patch/put operations use data from input filter

Following along with create(), update() and patch() should both use the values
present in the input filter, if present, over those passed to the method.

This patch introduces an abstraction, retrieveData(), that performs the work of
looking for the input filter and extracting values from it if found. It also
introduces tests for this specific functionality.
Remove code marks from headings

- per zfcampus/apigility-documentation#40
Merge branch 'hotfix/readme-formatting' into develop

Removes code markers from headings