the regexp that generates the error code needs some love.

[tjheffner]

two things:

1. It's duplicated in report.vue and result.vue. It needs to be in one place, and passed to these components. Probably as a global filter https://vuejs.org/v2/guide/filters.html, but maybe in the store

2. Needs correct handling for multi-rule issues, of which the only one it regularly bumps into is H53,ARIA6 (returning either one of H53 or ARIA6 will be a success. Currently returns "A6").