improve installation guide

@birgits : I would keep it more simple:

1. Download latest Anaconda for Python 3.x (64 or 32 bit)
2. Install Anaconda
3. Open the ‘Anaconda Prompt’ and create a virtual environment by typing:

   conda create -n yourenvname python=3.4
   activate yourenvname
   

   It is recommended to use python 3.4. Some users reported, that oemof does not work with Windows + Anaconda + Python 3.5
4. In ‘Anaconda Prompt’ type: pip install oemof
5. Install a Windows Solver if you want to use solph and execute the solph examples (See Run examples to check the installation ) to check if the installation of the solver and oemof was successful

[uvchik]

In an email you suggested to include a section with known installation problems with the following data: [OS | Python-Version | Python-Distribution? | number of reports | problem]. I think that is quite a good idea. It will just be difficult to keep it up to date since problems might be solved at some point and should be taken of the list. What do you think? I also think that the number of reports could serve as a good indicator as to whether it is a common problem or only one persons, but since there won’t be that many reports yet it might be unnecessary.

@birgits You are right. I thought the same, when I wrote the comment above. If we will have more such report we could open a wiki and link to the wiki. It is easier to keep a wiki up to date.

[uvchik]

Okay, will be release in the actual state.