Missing server side variable in custom script adapters

[sauzher]

Fix #396
Custom script adapters was unable to access those fields checked as "Server-Side Variable" despite of the description of that field parameter

collective.easyform/src/collective/easyform/interfaces/fields.py

Lines 175 to 179 in 77fbd60

	u"description_server_side_text",
	default=u""
	u"Mark this field as a value to be injected into the "
	u"request form for use by action adapters and is not "
	u"modifiable by or exposed to the client.",