Read text files as UTF-8 rather than binary
Read text files as UTF-8 rather than binary

* Non-US-ASCII characters make little sense in a binary encoding.
* Reuse helper for load_gemspec_uncached, see
  https://github.com/bundler/bundler/pull/6599/files

dilumnavanjana/bundler,bundler/bundler,dilumnavanjana/bundler,bundler/bundler,mvz/bundler,mvz/bundler