Implement async methods for AppEngineAPI...

... and the cache class.
Add async method for server/server_status
Update setup.py with evelink.appengine module
add async method to EVE on Google App Engine
Add async methods Map on Google App Engine
Fix doc
Add auto_async decorator which create async method

Only works for parameter-less methods
auto_call can deal with paramaters
Add auto_test_async_method decorator
Add async methods to Account for Google App Engine
Properly skip gae test when it's not available
Fix URLFetchServiceMock when run with nosegae
Fixed missing params in async methods
Add async methods for Char on Google App Engine
Refactor auto_call
Adds async methods to Corp on Google App Engine
Typo
Fixes some event related test.
update evelink.appengine __all__
Fix doc