CAS-1251: Possible Cross-Site Scripting on /login using execution parameter

Follow-up work on the previous commit around CAS-1251, this commit generalizes NoSuchFlowExecutionExceptionResolver to handle FlowExecutionRepositoryException is a common ancestor to webflow exceptions. Hiding these exceptions, such as BadlyFormattedFlowExecutionKeyException, would allow us to present the error page to the user as opposed to having the error rendered directly on the page which may include JS code passed to the /login CAS URI.

The HTMLEscaped handler is now removed, since it was originally intended for the webapp and not the management webapp.
CAS-1251: Possible Cross-Site Scripting on /login using execution parameter

Fixed tests
Merge pull request #199 from Unicon/CAS-1251-1

CAS-1251: Possible Cross-Site Scripting on /login using execution parameter