Add WS api/editions/preview

Provide ability to know what will be the effect of apply this specified new license to install an edition or update the existing one.

required permissions:

• system administrator

inputs:

• license

fails

• if an installation is in progress (either automatic or manual)
• when license can't be read
• when required fields can't be found (edition key and plugin list)

The WS response contains the following informations:

• the edition key read from the license
• flag indicating whether any change to SQ is required to update the license
  • NO_INSTALL
  • AUTOMATIC_INSTALL
  • MANUAL_INSTALL