[DS-1709] Improve clarity of access step UI

Clarify/fix default group selection

Show trail on access step
[DS-1707] Limit length of policy name
[DS-1706] Add review section for Access Step
Merge pull request #353 from aschweer/DS-1709-Access-Step-UI

[DS-1709] Access step UI
Merge branch 'master' into dspace-rest-fixes