Changed robots.txt to use disallow instead of allow
Fix session configs. Closes #1943.
Merge pull request #1876 from briankiewel/robots

Changed robots.txt to use disallow instead of allow
Fix spelling.
Added proper code for new maintenance mode feature.
Tweak maintenace mode handler.
Added clear compile pre update script.
Fix comment. Closes #1958.
Tweak composer commands. Closes #1954.