Adds new method set_argument() to GoclKernel
Improves logic in run_in_device() of GoclKernel
[doc] Updates GoclKernel section documentation
[doc] Adds documentation and annotations to GoclQueue
[doc] Adds documentation and annotations to GoclBuffer
[doc] Updates documentation of gocl-error
[doc] Adds documentation to GoclBufferFlags enum
Removes set_event() method of GoclEvent

The internal cl_event object can be se only upon creation of GoclEvent.
[build] Adds .gitignore files
[doc] Adds documentation and annotations to GoclEvent
[doc] Completes documentation of common Gocl declarations
[doc] Completes documentation of error management related API
Includes Gocl common declarations in global header
[doc] Adds documentation to all object class structures
[example] Updates hello-world example to use async API and adds hello-world-sync
[example] Adds Javascript version of hello-world example