Installation from requirements.txt

[dorianamouroux]

When transitioning from old school requirements.txt & pip install -r requirements to poet, it can be a lot of work, especially if in the requirements.txt file, the version are not set. Poet should have a command (or an option) to install the package from a requirements.txt file. Poet will then go through each of the dependencies, if the version is not defined, prompt the user with which version to install (by default = latest) and then add to poet.toml this dependencies.

After everything is finished, we can print to the user that he can safely remove requirements.txt