Checking if term is not wp_error before adding to collection
Merge pull request #170 from VarunAgw/important

Make sure `term` is not an error before using.

See #169
Not showing respondents page in SupportFlow in menu

There's no situation where someone would want to add a respondent term
directly, instead of adding them to the ticket, so the Respondents screen
should be hidden.

Fixes #166
Replaces usage of word respondent by customer

Just a case sensitive replace
Migrate all terms with taxonomy sf_respondent to sf_customer during upgrade