added license information to bower.json

We had problems getting any license information out the `flot.tooltip`package by using [bower-license](https://github.com/AceMetrix/bower-license) because neither `README.md` nor `package.json` are delivered by bower.

I simply added license information to `bower.json` to fix this.
Merge pull request #98 from mojoaxel/patch-1

added license information to bower.json