Add `pipenv add PACKAGE` sub command which replace `pipenv install PACKAGE`

Is your feature request related to a problem? Please describe.
pipenv install has two responsibilities:

• Install all packages in [packages] (bare pipenv install)
• Install specified package and update Pipfile and Pipfile.lock (pipenv install PACKAGE)

This make confused beginners.

Describe the solution you’d like
I suggest to add pipenv add PACKAGE which is equivalent to pip install PACKAGE and to make pipenv install PACKAGE deprecated.

Describe alternatives you’ve considered
Just remove pipenv install PACKAGE.

We are able to edit Pipfile If we want to add package.

Additional context

• yarn provides yarn add PACKAGE correspond to pipenv install PACKAGE. yarn install PACKAGE was removed.
• bundler does not provide sub command correspond to pipenv install PACKAGE

[techalchemy]

Internally the overlap should be cleaned up. From an api perspective, most users want to use high level commands like install so removing api functionality merely because of overlap seems unnecessary.

I’ll run this by Kenneth and see where we land. Initial pass on the workflow is intuitive enough.

[kennethreitz]

this is not happening