fixes #5191, #5193 - Rename system groups to host collections everywhere

This commit contains the changes needed to rename system groups to host collections
throughout the engine.  Summary of changes includes:
    schema migrations
    file renaming
    route updates
    model updates
    controller updates
    helper and lib updates
    view updates
    test/spec updates
    ui updates
    ui test updates
    ...
Merge pull request #4050 from bbuckingham/system-group-rename

fixes #5191/#5193 - rename System Groups to Host Collections