Fixed a typo in admin_page.php

I think it's a typo... :O)
Removed closing PHP tags and trailing whitespace.
Turned $mapply_db_version to a constant.
Merge pull request #1 from dbernar1/patch-1

Fixed a typo in admin_page.php
Merge pull request #2 from dbernar1/no-closing-php-tags

Removed closing PHP tags and trailing whitespace.
Merge pull request #3 from dbernar1/version-constant

Turned $mapply_db_version to a constant.