Initial version of Rest service Integracion layer.
It includes support API for GET, DELETE, POST and PUT requests.
Complete tests cases have also been developed.
Javadoc documentation
Paged Query
Client Rest Caching.
Caching criteria is defined by server in response headers, so client
logic must analyze them and manage data caching.
Appverse rest persistence layer (as rest client function) supports:

-CacheControl Max-age directive (HTTP 1.1):
By sending max-age directive, server defines a time period while it's
supposed that data is not going to be modified, so client shouldn't ask
for same data.

-EntityTag Header (HTTP 1.1)
By returning http EntityTag header, server is identifing data object
with a hash code.
Client should send this header in next requests to allow server to check
if data object has changed for same request parameters.
If data object has not been modified, server will return a NOT_MODIFIED
status, avoiding to send the entire message data.


https://devcenter.heroku.com/articles/jax-rs-http-caching
gitignore
remove .gwt log folder
add .gwt log folder to ignore
Merge branch 'master' of https://github.com/sergiorc/appverse-web into sergiorc-master

Conflicts:
	showcases/appverse-web-showcases-gwt-rest/appverse-web-showcases-gwt-gwtfrontend-rest/.gitignore
updated version
Added headers