[gh-852] Update Entity API module to 7.x-1.5

Also remove README note as this version contains the URI callback
fix: http://drupal.org/node/1481372
[gh-852] Update ctools module to 7.x-1.4
[gh-852] Upgrade webform to 7.x-3.20
Merge pull request #853 from ericras/issue-852

Closes #852 Security updates to webform, entity, ctools