add begin rescue block for JSON requests

returns JSON error with name of exception

[#61768664]
Revert "add begin rescue block for JSON requests"

This reverts commit 574a960165a2f4fc45e92f5fc544e4dddd3230f7.
for all exceptions return proper response type

For JS requests, return JSON and for HTML requests return HTML
improve error messages after votes, skips, etc.

For any Ajax action that has an error we will parse the JSON to look for the
error name. Right now, we're looking only for CantFindSessionFromCookies since
we already had a message for that. If the user gets an error that we're not
explicitly looking for then it'll display a generic error message with that
error name. We also have error messages for timeouts of requests or requests
that got cancelled.

[#61768664]
ensure error responses are JSON for JS requests
update Changelog
Merge pull request #28 from allourideas/better-ajax-error-messages

Better ajax error messages