Implement ewk_context_favicon_database_directory_set()

Implement ewk_context_favicon_database_directory_set()

There is no implementation of ewk_context_favicon_database_directory_set()
api. This patch adds missing implementation. It will set directory path
to argument passed and filename to default one.

Original beta/m42_2311_t patch:
- http://165.213.202.130/gerrit/#/c/85276/

Bug: http://107.108.218.239/bugzilla/show_bug.cgi?id=14792

Reviewed by: a.renevier, d.waslicki, djmix.kim, msu.koo, sns.park

Change-Id: Ic525ba7e0c9e39e8e91ab480cc5852f5d530a363
Signed-off-by: Marcin Niesluchowski <m.niesluchow@samsung.com>