Improve out of box experience and management of terms

[jmealo]

• [ ] Have slate on setup initialize a current and next school year term
• [ ] All tools should deal gracefully with there being no current term
• [ ] All tools that can should use the Term::getClosest() call rather than Term::getCurrent() if possible
• [ ] The term editing GUI should be hardened for production use

[themightychris]

I don't agree that renest should ever be run automatically, there is no situation where the renest would be necessary other than when a developer manually edits tables and it could be destructive to a table needing repair. There are three things we should focus on to improve term issues:

1) Have slate on setup initialize a current and next school year term 2) All tools should deal gracefully with there being no current term 3) All tools that can should use the Term::getClosest() call rather than Term::getCurrent() if possible 4) The term editing GUI should be hardened for production use

[jmealo]

@themightychris updated ticket to reflect work to be done