Make the isLoggedIn function more efficient.

Multiple calls to this function resulted in multiple database calls. The
isLoggedIn variable is now cached in the DIC.
Add isLoggedIn performance fix to changelog.
Don't sort on keys, as we want the given sequence to be respected.

Will fix https://github.com/forkcms/forkcms/issues/828
Updated changelog
Update returns number of updated rows, which will be always 1 in our case
Use the correct id

Will fix #798
Updated changelog
Removed locale
Removed styling
Don't use the feedburner-setting anymore
Remove the feedburner-field from the settings page
Don't set a default value for the feedburner setting
Remove the helpmessage
Updated changelog
Merge branch 'master' into 828-respect-sequence

Conflicts:
	CHANGELOG.md
Merge branch '828-respect-sequence'
Merge branch 'master' into 798-wrong-item-was-hilighted

Conflicts:
	CHANGELOG.md
Merge branch '798-wrong-item-was-hilighted'
Merge branch 'master' into 693-remove-feedburner

Conflicts:
	CHANGELOG.md
Merge branch '693-remove-feedburner'