Add encoding: utf-8 tags to source files.
Meet terms of Apache 2.0 License

- Formalize existing Apache 2.0 License Terms according to license
requirements.
- Add LICENSE.txt file with Apache 2.0 license text.
- Updated contributors.
No longer using RVM so remove .rvmrc from .gitignore
Add missed license text.
Change from simplecov and guard to coco and rerun respectively.
Typo
Update Rake TestTask syntax to one that throws no warnings.
Fix formerly skipped spec when a String share of unexpected format is passed as an arg.
Resolve 200+ issues reported by rubocop.

Rubocop applies the Ruby community style guide to Ruby code and
highlites issues with style and complexity.

See : https://github.com/bbatsov/rubocop

There are no functional changes or changes to specs to resolve these
issues.  All developers should run rubocop before submitting pull
requests.
Refactor Shamir#<<(share)

- Don’t fail if a share has already been added. Just skip it.
- Don’t fail if the number of shares added is more than needed, only
fail if shares provided exceeds max number of shares represented by @n.
 In other words, you can’t add more shares than were originally
generated.
- Add spec to cover adding mix of valid and invalid shares. This *will*
return a secret, it just won’t be the right one!
Removed deprecated method Share#from_string

You can do the same with Share#new(share_string)