Use original gem gollum-lib

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Gollum use own constant now

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Fix test broken by 89c942908cc1d98dfd4af1f89b69704f691a0edf

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
 Merge branch 'gollum-lib' into 'master'

Use original gem gollum-lib
Update grape-entity

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>