Nullable and defaults

[Synicix]

• Redesign the way the input blocks and generated for datetime, timestamp, and date to handle default value and current state.
• Added support for reseting to null or default for insert and update (Update the resetToNullOrDefault function in insert tuple to match discussed behavior #48) PR Nullable and defaults #93
• Added support to render default values if exist for insert (Render default values if default values exists when the user open up insert wihtout something checked #95) PR Nullable and defaults #93

[guzman-raphael]

Minor doc nits. Also, please update the body of the PR with summary. Usually just copying over the diff on CHANGELOG.md is sufficient. Oh and update milestone / project for to update the progress.