Osgi problem Import-Package org.mortbay.util.ajax is not optional

[tomdw]

In the current manifest of the atmosphere runtime the package import org.mortbay.util.ajax is not optional. Although it is only really necessary when running Jetty Comet support on an old jetty version.

Please make it optional as it requires us adding old jetty bundles which we otherwise do not need.

[jfarcand]

Can you do a pull request with the exact change you did? You will save me a few cycle :-) Thanks!