Make sure resource links in published content use md5 hash

This can be revoked when "files" table is migrated to use sha1 hash
Fixes issues with updates on license and role acceptance upserts.
Merge pull request #40 from Connexions/fixes

Fixes issues with updates on license and role acceptance upserts.
Merge pull request #39 from Connexions/fix-resource-hash

Make sure resource links in published content use md5 hash
Add valdations for meatadata
Tests for validation functions
Validation for HTML content references.
Test for a successful publication of document pointer references.
Check for document pointer validity on persistence of a pending binder.
Fix derived-from validator conditional table query and operators.