Update XsdDocumentedTests to make easier to understand problems
SEC-2098, SEC-2099: Created HeadersFilter

Created HeadersFilter for setting security headers added including a
bean definition parser for easy configuration of the headers. Enables
easy configuration for the X-Frame-Options, X-XSS-Protection and
X-Content-Type-Options headers. Also allows for additional headers to
be added.
SEC-2098, SEC-2099: Polishing
- Created HeaderFactory abstraction
- Implemented different ALLOW-FROM strategies as specified in the proposal.

Conflicts:
	config/src/main/java/org/springframework/security/config/http/HeadersBeanDefinitionParser.java
	config/src/test/groovy/org/springframework/security/config/http/HttpHeadersConfigTests.groovy
SEC-2098, SEC-2099: Fix build

  - hf.doFilter is missing FilterChain argument
  - response.headers does not contain the exact values for the headers so
    should not be used for comparison (note it is a private member so this
    is acceptable)
  - hf does not need non-null check when hf.doFilter is invoked
  - some of the configurations are no longer valid (i.e. ALLOW-FROM
    requires strategy)
  - Some error messages needed updated (some could still use improvement)
  - No validation for missing header name or value
  - rebased off master / merged
  - nsa=frame-options-strategy id should use - not =
  - FramewOptionsHeaderFactory did not produce "ALLOW-FROM " prefix of origin
  - remove @Override on interface overrides to work with JDK5