mock/rest: Move common functionality in __init__ and remove basetest.py
mock/rest: Fix typos in the README
mock/rest: Update README with more TODOs
mock/rest: move _create_test_folder() helper to common base class

we are going to need it elsewhere too in future
mock/rest: Change signature for _create_test_folder

now it directly returns created folder ID
mock/rest/test: Create test data for 'folder exists' test
mock/rest: Update API documentation to latest version v0.1
rest/api-doc: Fix text formatting so sections are rendered properly