Make selection behaviour match ember-frost-list

[AdamWard1995]

This project uses semver, please check the scope of this pr:

• [ ] #none# - documentation fixes and/or test additions
• [X] #patch# - backwards-compatible bug fix
• [ ] #minor# - adding functionality in a backwards-compatible manner
• [ ] #major# - incompatible API change

This PR prevents text from being selected when doing a range select and when clicking on a row body (as opposed to the checkbox) that row will be the only selected one

CHANGELOG

• Fixed selection functionality to match ember-frost-list

[coveralls]

Changes Unknown when pulling b97848c3d1cda6083dbce2ca11273635c6c45da0 on AdamWard1995:fix_selection into on ciena-frost:master.

[coveralls]

Changes Unknown when pulling 01d052d9099a9ba27668e60a96772528d3b05c54 on AdamWard1995:fix_selection into on ciena-frost:master.

[coveralls]

Changes Unknown when pulling b1e11f383994917e31cf6726c6edef27ae78d163 on AdamWard1995:fix_selection into on ciena-frost:master.

[quincyle]

Approved