Better chance of running with Content Security Policy rules

OpenLayers cannot run in environments where CSP (http://en.wikipedia.org/wiki/Content_Security_Policy) is enforced - for example a Firefox extension that doesn't allow dynamic code evaluation (with `eval`).  We still conditionally use eval in the JSON parser, but this can be avoided by developers using native JSON.parse before calling our GeoJSON parser, for example.
Adding a bit about the CSP change to the release notes
Merge pull request #1005 from tschaub/csp

Better chance of running with Content Security Policy rules