Removed the unused setting 'session.payload'.

Signed-off-by: Isern Palaus <ipalaus@ipalaus.es>
Merge pull request #1999 from ipalaus/fix/session-payload

Removed the unused setting 'session.payload'.
Added sendmail path config option.
Updated available drivers for mail.
New welcome page.
Merge pull request #2018 from laravel/welcome-page

New welcome page.
Just boot MbString on Patchwork.
Fix casing.