Store google adunit on each div allow refreshing of ads

Ads are now refreshed if a display request is sent for them more than
once… more work to do here though I think.
Removing console.log call
add link to dfp help for custom targeting
Merge pull request #24 from crccheck/readme-custom-targeting-link

add link to dfp help for custom targeting
Variable name tidy up and optimisations
Simplified getName function
Re minified and bumped version
Merge branch 'master' into refresh-existing
Updating readme
Optimising code
Tidying up undefined checks
More optimisations
Merge branch 'master' into optimisations
Made compatible with Zepto.js and Tire.js and a few more small optimisations.
Reverted tinkering code in dfpLoader
Updating readme
Fixing image.
Merge pull request #29 from coop182/update-readme

Update readme
Added demo/ad unit tester link
Category exclusion added.