DRAFT: Adds web command

[MatheusRich]

Description:

Closes rubygems#2784.

Ruby claims to be "a programmer's best friend", and focus on "simplicity and productivity". As rubygems is now part of Ruby, I think it should follow those principles too.

I'm integrating gem-web into rubygems as part of GSoC 2019. This new command allows user to quickly find documentation of a gem.

I think this is specially good when one's not sure about what a gem does, or is confused with its name. Maybe the user wants to quickly check the rubygems' page of some gem (to check versions, dependencies, etc). With this command the access will be faster and easier with just one command on the terminal. Other use case could be opening the documentation for a gem, which improves productivity.

The usage would be like this:

gem web rails # Opens github

Options:
  -g, --github                     Open GitHub page of gem, this searches all urls for a GitHub page. This is the default.
  -c, --sourcecode                 Open sourcecode gem
  -d, --doc                        Open documentation of gem
  -w, --webpage                    Open webpage of gem
  -t, --rubytoolbox                Open the rubytoolbox page for that gem
  -r, --rubygems                   Open the rubygems page for that gem

Let me hear some feedback about this.

Platforms manually tested:

• aix
• cygwin
• darwin
• macruby
• freebsd
• hpux
• java
• dalvik
• dotnet
• linux
• mingw32
• netbsdelf
• openbsd
• bitrig
• solaris

Tasks:

• Describe the problem / feature
• Write tests
• Write code to solve the problem
• Get code review from coworkers / friends

I will abide by the code of conduct.

[zoras]

Nice 👍
Do make sure to add opener command for all supported OS.
Platform is already detected/known from here: https://github.com/rubygems/rubygems/blob/master/lib/rubygems/platform.rb#L79

[zoras]

Looks good Matheus. It would be great if we could do QA test on the various supported platforms as well as unsupported ones. Maybe you can try it out for various OS with VirtualBox?