Merge tag '1.5.2' into develop

Release: 1.5.2
Preparation for new development cycle after release 1.5.2
Various changes

- Use HTML Builder class
- Always return output. Remove the echo option.
Move rendering to separate class for ShowcaseCompetitionThumbnails
Add Twig to composer
Add upload dir and template dir to the settings
Make use of twig for two methods

- The facebook image
- The Monthly Entries
Rename templates
Convert Showcase to twig
Use separate caption data
Add image szie
Can't have multiple sessions.
Creation of common thumbnails fails
Fix masonry for Chrome
Use twig for Category Winners
Update documentation.
Use twig for shortcode Person Winners
Clean up and small fix
Reformat code
Make sure to load minified scripts in production