Remove group size columb from group list screen
Fix group list table's action marker column width
pep8 fixes
Display the number of contacts in a group in the info message displayed when displaying the group's contacts
Merge branch 'develop' into feature/issue-627-display-size-of-group-in-contact-details-screen-instead-of-contact-list-screen
Merge branch 'feature/issue-627-display-size-of-group-in-contact-details-screen-instead-of-contact-list-screen' into develop