Check javascript licenses during build configuration.
A check is run to make sure all licenses (with a few exceptions) are the same for the files that go into webodf.js.
Merge pull request #625 from vandenoever/checklic

Check javascript licenses during build configuration.
Add a very basic JS injection attack document & test
Add getElementsByTagName to DomUtils.
Remove dangerous <script/> and <style/> tags before inserting XML into the dom.
<script/> tags are executed when inserted into the DOM. This is unwanted, so they are are removed before the XML is inserted into the DOM.
In addition, <style/> elements can be used to execute code, so they are removed too.
Remove event handler attributes: attributes that have no namespace and a name starting with on.
Add tests to check if dangerous input is loaded without executing javascript.