genlist: Implemented genlist expand mode and content_min_limit function

genlist: Implemented genlist expand mode and content_min_limit function

Summary:
1. Implemented genlist mode ELM_LIST_EXPAND
2. Implemented content_min_limit function which override scroll interface.
  This function will be used by call API elm_scroller_content_min_limit.
  This function will set the object minimum size as its scroll content size,
  if parameter value is EINA_TRUE.

@feature

Test Plan: Add new test case in test_popup.c

Reviewers: raster, seoz

Subscribers: stefan_schmidt, bluezery

Differential Revision: https://phab.enlightenment.org/D1279