Reword available explanation

In this merge request, the following is changed:

• The "available" quarter explanation is changed to explain that an available quarter is when a quarter allows students to submit availability.
• The exceptions for quarters and dates which are not available are merged into one exception.

added 7 commits

• cfb09312...0ba64619 - 6 commits from branch dev
• 1c102529 - Reword available explanation

Compare with previous version

By Max van Deursen on 2018-06-04T08:32:14 (imported from GitLab project)

merged

By Max Pigmans on 2018-06-04T15:59:21 (imported from GitLab project)

mentioned in commit b5afc0d3

By Max Pigmans on 2018-06-04T15:59:21 (imported from GitLab project)