Leginon

r16545 adds subclasses of Calibrator in tables to search for node settings.

In the future, it should search database table to generate the search table.

Testing:
1. start a Leginon session as one user.
2. change settings of a node in Calibrations application and close Leginon
3. use myamiweb/revertsettings.php to revert settings to a previous session of the same user.
4. continue on the same session as the same user. The settings should be reverted.

Any Leginon user can test.

Need to be merged to 2.2 after testing.