WIP: Address Issue #431

[jmrocha]

This is a work-in-progress pull request to address issue #431.

• Install eppy and fetch input files online;
• Fix cell errors because of Python v2 syntax.

Additional suggestions:

• Show images using Markdown instead of Python;
• Add instructions on how to build the docs locally;
• Import the IDF object from the eppy package instead of the modeleditor module to abstract the package's internal structure.
• Rewrite sections of the notebook to incorporate a formal tone or enhance conciseness.

Notebooks:

• Main_Tutorial.ipynb;
• Outputs_Tutorial.ipynb;
• HVAC_Tutorial.ipynb;
• newfunctions.ipynb;
• runningeplus.ipynb;
• usefulscripts.ipynb.

[jmrocha]

I had to re-run all cells to check if there was any error and, consequently, all cells had their execution counter updated (e.g., In[186]: -> In[105]:). This caused a lot of changes which makes it difficult to understand what was essentially changed.