Fix exception preventing proper shutdown of Atmosphere.

[seamusmac]

This allows for redeploy to properly work.

[seamusmac]

When testing hot redeploy for an application I have that uses the Shiro framework, I found that while the shutdown happens, I was getting the following exception:

org.apache.shiro.UnavailableSecurityManagerException: No SecurityManager accessible to the calling code, either bound to the org.apache.shiro.util.ThreadContext or as a vm static singleton. This is an invalid application configuration. at org.apache.shiro.SecurityUtils.getSecurityManager(SecurityUtils.java:123) ~[shiro-core-1.2.4.jar:1.2.4] at org.apache.shiro.subject.Subject$Builder.<init>(Subject.java:627) ~[shiro-core-1.2.4.jar:1.2.4] at org.apache.shiro.SecurityUtils.getSubject(SecurityUtils.java:56) ~[shiro-core-1.2.4.jar:1.2.4] at org.atmosphere.cpr.AtmosphereRequestImpl.getSession(AtmosphereRequestImpl.java:694) ~[atmosphere-runtime-2.4.5.jar:2.4.5] [2 skipped] at org.atmosphere.cpr.SessionTimeoutSupport.restoreTimeout(SessionTimeoutSupport.java:69) ~[atmosphere-runtime-2.4.5.jar:2.4.5] at org.atmosphere.cpr.AtmosphereResourceImpl.cancel(AtmosphereResourceImpl.java:817) ~[atmosphere-runtime-2.4.5.jar:2.4.5] at org.atmosphere.cpr.AtmosphereResourceImpl.close(AtmosphereResourceImpl.java:900) ~[atmosphere-runtime-2.4.5.jar:2.4.5] at com.ardan1.config.AFramework.closeAtmosphereResource(AFramework.java:16) ~[classes/:na] at org.atmosphere.cpr.AtmosphereFramework.destroy(AtmosphereFramework.java:1806) [atmosphere-runtime-2.4.5.jar:2.4.5]

This prevents a proper shutdown from working. If I catch the exception, everything works as expected.

Do you guys think this is a change that can be merged?

[seamusmac]

@elakito @jfarcand Is this change ok?

[elakito]

@seamusmac I merged it. Thanks.