Conda support

[0Xellos]

The present options for autodetecting virtual environments (-p switch) work for virtualenv and venv, but not conda, which sets sys.base_prefix and changes sys.prefix to the same value as sys.base_prefix.

My fix also checks if the environment variable CONDA_PREFIX is set and uses base_prefix as the environment directory in that case.

[ekalinin]

Hey @0Xellos!

Thanks for patch. Could you fix too long line?

https://travis-ci.org/ekalinin/nodeenv/jobs/342802175#L530

[0Xellos]

Fixed.

[ekalinin]

Thanks!