Revert use of putAll for JSF spec compliance

Issues: SWF-1532
Remove spring-webflow-samples directory

The new home for the samples will be:
https://github.com/SpringSource/spring-webflow-samples
Add Gradle build

- Add gradle build script
- Remove spring-build/
- Remove build-spring-webflow/
- Remove ivy.xml, pom.xml, template.mf
- Remove eclipse  metadata
- Remove RichFacesAjaxHandler.java
- Create src/dist and add changelog.txt, readme.txt

Dependency changes:
- EBR dependency -> Maven-central dependencies
- el-api 1.0 -> 2.2.0
- ognl 2.6.9 -> 2.6.11
- org.jboss.el -> tomcat-jasper-el 7.0.27
Add reference docs tasks to Gradle build

- Move spring-webflow-reference to src/reference
- Upgrade to Docbook 5
- Apply docbook plugin
- Add tasks for generating distribution zip files
Add spring-js-resources to Gradle build
Add Eclipse import script based on Gradle build
Rename a couple of test classes to match convention
Update build instructions in README
Apply Gradle group id to root project as well
Upgrade spring-faces to JSF 2 as a minimum requirement

* Rework all state handling, removed FlowSerializedView class and save
state as opaque object
* Use FacesWrapper classes instead of custom delegates
* Deprecate isAtLeastJSFXXX() methods and removed all internal use
* Remove all Jsf2XXX versions of classes
* Refactor all calls to deprecated JSF methods
* Removed older VariableResolver and PropertyResolver classes
* Deprecate Jsf2FlowResourceResolver and log warning if used
* Create new FlowELResolver to replace removed VariableResolvers and
PropertyResolvers
* Update faces-config.xml to use newer xsd
* Significantly rework FlowFacesContext to remove the message delegate
and generally improve the code
* Added "provided" dependency to MyFaces and fixed partial state saving
on MyFaces
* Fixed FlowResourceResolver to delegate to both MyFaces or Mojarra
depending on availability
* Add JsfUtils.findFactory method and rework existing code to replace
FactoryFinder calls and casts
* Refactor JsfViewFactory to improve code readability
* Rename FlowViewStateManager and FlowViewResponseStateManager to
FlowStateManager and FlowResponseStateManager
* Ensure ResponseContextHolder is reset after each test
* Update JSF portlet support to function with JSF 2.0

Issue: SWF-1536, SWF-1540, SWF-1550
Merge pull request #13 from philwebb/SPR-1550

* SWF-1550:
  Upgrade spring-faces to JSF 2 as a minimum requirement
Update .gitignore to filter gradle-app.setting
Upgrade Gradle to release 1.0
Ignore eclipse WTP generated META-INF folders
Modify <faces:resources> to add portlet variant

The ResourcesBeanDefinitionParser will now automatically register an
additional portlet resource resolver when a portlet environment and
and relevant Spring portlet classes are detected.

Issues: SWF-1500
Merge pull reqest #14 from philwebb/SWF-1500

* SWF-1500:
  Modify <faces:resources> to add portlet variant
Remove legacy code following JSF 2.0 migration

- Remove JSF 1.2 components including ui package, faces-config.xml
  references and tld files
- Remove AjaxViewRoot class
- Polish JavaDocs

Issues: SWF-1536
Update ref docs for JSF and Portlet updates

Issues: SWF-1553
Fixed link error in ref docs

Issues: SWF-1553
Add option to save Web Flow output to MVC flash scope

Output from a flow can now be saved to the flash scope of Spring MVC
when the 'saveOutputToFlashScopeOnRedirect' property of the
FlowHandlerAdapter is 'true'.

For backwards compatibility this is an opt-in feature that must be
configured by the user.

Issues: SWF-1561