Fix trailing os dir separator

user are able to include a trailing slash/backslash. This causes `displayShow.tmpl` to eat the first character of the filename of a show. This patch ensures the os dir separator is removed if present.

STR the issue:
1. add an existing show. Note trailing os sep **isn't** present. Say path is `/some/show/test`.
2. Edit show
3. manually edit the location text field to read `/some/show/` (not trailing os sep **is** present)
4. Save

Path now contains a trailing os sep.