fixes #313 - Edit multiple hosts returns 404

Minor html layout formatting fixes

fixes #383 - Foreman may not start up at all upon new installations

Fixes #239 - Erases environments and puppetclasses

The fix also includes a page in which the use selects the additions
and removals which they would wish to apply to their database.
Errors are reported and an opportunity is given to reapply the changes.

XHTML compliance

Fixes #294 Convert settings to a dropdown

Fixes #218 - Search hosts by puppetclass

fixes #372 - add search option for disabled hosts

fixes #371 - disable many hosts at once

refs #369 - removing extra table header