Use internal WWsafe.pm instead of system Safe.pm
Fix default address for libraries.

correct library to libraries
Obtain version number from file VERSION (variable name: $WW_VERSION)
Merge pull request #86 from openwebwork/hotfix1

Hotfix1
Update math4.css

Addressed bug 2647
Fixed broken disabled buttons
Merge pull request #96 from goehle/upgraded2.7

Fixed broken disabled buttons
Merge branch 'master' of https://github.com/openwebwork/webwork2