string-bundle: use string-template module instead of _.template

[go-oleg]

While working on https://github.com/juttle/atom-juttle-viewer/pull/1, ran into the problem that atom doesn't allow usage of _.template (see discussion). We use _.template to generate runtime messages and parameter validation error messages.

We don't need everything that _.template offers, just basic string templating, so switch to https://www.npmjs.com/package/string-template.

Changes necessary to make this work

• Switching from {{ and }} as the delimiter to string-template's { and }.
• Remove the redundant info nesting in param validation messages. string-template doesn't support nesting and its also just not necessary here.

@mnibecker

[mattnibs]

+1