Avoid open-ended dependencies
Avoid open-ended dependencies

Running `rake install` always resulted in these warnings:
```
WARNING:  open-ended dependency on clocale (>= 0) is not recommended
  if clocale is semantically versioned, use:
    add_runtime_dependency 'clocale', '~> 0'
WARNING:  open-ended dependency on filesize (>= 0) is not recommended
  if filesize is semantically versioned, use:
    add_runtime_dependency 'filesize', '~> 0'
WARNING:  open-ended dependency on manpages (>= 0) is not recommended
  if manpages is semantically versioned, use:
    add_runtime_dependency 'manpages', '~> 0'
WARNING:  open-ended dependency on rainbow (>= 0) is not recommended
  if rainbow is semantically versioned, use:
    add_runtime_dependency 'rainbow', '~> 0'
WARNING:  open-ended dependency on diffy (>= 0, development) is not recommended
  if diffy is semantically versioned, use:
    add_development_dependency 'diffy', '~> 0'
WARNING:  open-ended dependency on rake (>= 0, development) is not recommended
  if rake is semantically versioned, use:
    add_development_dependency 'rake', '~> 0'
WARNING:  open-ended dependency on ronn (>= 0, development) is not recommended
  if ronn is semantically versioned, use:
    add_development_dependency 'ronn', '~> 0'
WARNING:  open-ended dependency on rspec (>= 0, development) is not recommended
  if rspec is semantically versioned, use:
    add_development_dependency 'rspec', '~> 0'
WARNING:  open-ended dependency on rspec-its (>= 0, development) is not recommended
  if rspec-its is semantically versioned, use:
    add_development_dependency 'rspec-its', '~> 0'
WARNING:  open-ended dependency on rubocop (>= 0, development) is not recommended
  if rubocop is semantically versioned, use:
    add_development_dependency 'rubocop', '~> 0'
WARNING:  open-ended dependency on rubocop-rspec (>= 0, development) is not recommended
  if rubocop-rspec is semantically versioned, use:
    add_development_dependency 'rubocop-rspec', '~> 0'
WARNING:  open-ended dependency on rubygems-tasks (>= 0, development) is not recommended
  if rubygems-tasks is semantically versioned, use:
    add_development_dependency 'rubygems-tasks', '~> 0'
WARNING:  See http://guides.rubygems.org/specification-reference/ for help
```

- use pessimistic version constraints for all dependencies in the gemspec

athityakumar/colorls,athityakumar/colorls