Fix installation permissions

[Victor-Savu]

Avoid having to use superuser (administrator) privileges for platforms where the global pip installation directory is not writable by the regular user.

Se pip help install | grep -A 4 -e '--user':

  --user                      Install to the Python user install directory for
                              your platform. Typically ~/.local/, or
                              %APPDATA%\Python on Windows. (See the Python
                              documentation for site.USER_BASE for full
                              details.)

Docs for site.USER_BASE.

Fixes:

• Poetry fails to install on macOS High Sierra using Homebrew Python 3 #59

Open questions:

• Should this be optional? If so, should it be opt-in, or opt-out?
• Should we prompt the user that the user install directory (site.USER_BASE) needs to be in the $PATH / %PATH% variable in order for poetry to be recognized as a command?

[cauebs]

It appears to have worked.

~ $  curl -sSL https://raw.githubusercontent.com/Victor-Savu/poetry/patch-1/get-poetry.py | python
Retrieving metadata

Installing version: 0.10.2
  - Getting dependencies
  - Vendorizing dependencies
  - Installing poetry

poetry (0.10.2) successfully installed!
~ $ poetry --version
Poetry 0.10.2

[jgirardet]

I proposed sudo in #163
but I agree --user is better

[Victor-Savu]

@jgirardet To be honest, I am a bit worried by the idea that different packages live in different places :) However, I would like this to work for people who either don't have the privilege of sudo, or who simply don't feel like they want to bestow their software unto all the users of the system.

[Victor-Savu]

@sdispater Do you have any suggestions or preference regarding the two open questions in this PR?

[ranisalt]

The README instructions are broken because of this missing flag, yet it does not seem to be priority.

[sdispater]

Closing since with with the new installer permissions error should no longer exist.

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.