Fix 224 inconsistent bounds

[cehbrecht]

Pull Request Checklist:

• This PR addresses an already opened issue (for bug fixes / features)
  • This PR fixes issue inconsistent bounds (lat_bnds etc) after subset operation #224
• Tests for the changes have been added (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)
• HISTORY.rst has been updated (with summary of main changes)
• I have added my relevant user information to AUTHORS.md

• What kind of change does this PR introduce?:

Bug fix

• Does this PR introduce a breaking change?:

no

• Other information:

[cehbrecht]

Changes:

• pin roocs-utils < 0.6 ... will be addressed with a new PR
• adds method _remove_redundant_coordinates_from_bounds to fix issue inconsistent bounds (lat_bnds etc) after subset operation #224
• updated method _remove_redundant_fill_values to remove all fill-values ... including height (see issue File metadata change when subsetting data #198)
• added tests

[cehbrecht]

@agstephens merging to get things in place.