UP-4205 Add and map Filter blocking CVE-2014-4172 .

Adds a Filter for sanitizing request parameters and configures this Filter to block `CVE-2014-4172`, an illicit proxy vulnerability in the Java CAS Client version included with uPortal releases and present on the uPortal 4.0 patches branch.

Tracked in JIRA at [UP-4205](https://issues.jasig.org/browse/UP-4205).

This Filter blocks the vulnerability and is an alternative to addressing this issue with more change (namely, upgrade to Java CAS Client v 3.3, which has different dependencies and slightly different configuration than the Java CAS Client 3.2 in use in uPortal 4.0.).

This Filter is a fork of and application of https://github.com/Jasig/cas-server-security-filter/pull/6 .  Including the Filter directly in the uPortal codebase prevents having to modify `pom.xml` to pull in new or different dependencies (and allows uPortal not to wait for this Filter to appear in a dependency available from Maven Central).
Seems like a lot of common code in every test, might be worth moving common code to a `@Before` method.

http://junit.sourceforge.net/javadoc/org/junit/Before.html