Support the '!' character when configuring default action for a portlet mode in portlet.xml

Supporting the '!' will make it possible to configure a method for the action mapping for the default action in a portlet mode.

Example:

<init-param>
<param-name>defaultViewAction</param-name>
<param-value>index!input</param-value>
</init-param>

Very useful when the default action for a mode contains a form that is usually displayed using the "input" method.