ApplicationConfig: Made the javadoc more consistent.

Applied the following format for all configuration values:

Text text text.
<p>
Default: default value<br>
Value: org.atmosphere.value
Merge pull request #1132 from slovdahl/master-slovdahl

ApplicationConfig: Made the javadoc more consistent.
HeartbeatInterceptor: Force use of AsyncIOWriter.

Without forcing AsyncIOWriter to be used only the first heartbeat is sent when using SSE.
Merge pull request #1134 from slovdahl/master-slovdahl

HeartbeatInterceptor: Force use of AsyncIOWriter.