Fix study name returned

It must be trial name, not label from tree
Study name shown with /studies is wrong

Before this fix we showed folder name as study name.
It could be that folder name on the DSE tree does not match with actual study id.
We shuld use "study id" (aka trial id) as name of the study instead,
so /studies/<study name> always works.
Rename name field to id one in Study
Remove checking study node by visual attribute

For study check it's sufficient to have trialNode with such path.
Visual attribute check use to be inexpensive study check
before making another db query as fallback one.
But it does not work for that reason anymore as we need trialNode anyway now.
Reinstate term to study conv optimization
Fix isSynonym condition
Transient field is overriden by subclass

This is grails bug that apears againg https://jira.grails.org/browse/GRAILS-7748
Add test for the two last commits
Merge pull request #52 from thehyve/issues/study-name-is-wrong

Issues/study name is wrong