A minor refactoring and bugfix release with improvements to strengthen password hashing.

Changelog:

• Switched to more appropriate password hashing algorithm (bcrypt) and the native hash_password() function.
• Added 'expiresOn' and 'lastUpdated' to the content object table as hooks for future functionality.
• Added 'module' as an additional column in the taglinks table to allow taglinks to be filtered by module.
• Locked user-side gallery to image type objects, rather than returning all images from all object types.
• Adopted usage of null coalescing operator (PHP 7) to shorten relevant ternary expressions.
• Renamed TfAngryTree to Tftree.
• Removed TfSecurityUtility (consolidated into TfUtils).
• Removed TfCriteriaItemFactory (items are now handled as part of TfCriteriaFactory).
• Added missing TfBlockHandler.
• Fixed bug related to search operator in TfSearchContent.
• Fixed offset bug recently introduced to pagination control.