Add support for using conda environment.yml file as pyup requirements file

[bourque]

Anaconda users often manage their software environment from a requirements file called environment.yml See docs here. Here is an example of this (from the conda docs):

name: stats2
channels:
  - javascript
dependencies:
  - python=3.4   # or 2.7
  - bokeh=0.9.2
  - numpy=1.9.*
  - nodejs=0.10.*
  - flask
  - pip:
    - Flask-Testing

It would be useful and less redundant for developers using conda if pyup could also use this file as a requirements file. Currently, pyup is able to read this file, but only builds requirements listed under pip (in this example, Flask-Testing). It would be useful if pyup could robustly read the requirements listed under dependencies and not specifically listed under pip.

[alimanfoo]

Just to add this would be super helpful for us. Also, this would obviously need to take account of the channels specified in the environment.yml file when searching for available upgrades.

[rafaelpivato]

It would be great if all our dependencies could be handled by pyupio/dparse project as well.

[ericmjl]

I'd like to add in a vote for environment.yml support please!