Issues discovered during QA for #132

[thelmick-unicon]

Three issues to address:

1. The indent level for level one should be shifted to the left to align with level one tags. It is currently indented to the same level as level two.
2. The cancel/save buttons for all sub-tag levels are not aligned to the right the way the first level is.
3. Extra period in the error message when a tag already exists
4. When a tag is renamed to a name that's already used, the error message shown to the user should be an explanation that the tag name already exists. Current behavior: there's a generic AxiosError message, see screenshot.