Update gpkitmodels to gplibrary

I was trying to install the model to figure out how to use Sankey, when I ran into this error
```python
$ pip install -e solar
Obtaining file:///C:/Users/Berk/Dropbox%20%28MIT%29/MIT%20Graduate%20School/code/solar
Requirement already satisfied: numpy in c:\users\berk\anaconda2\lib\site-packages (from solar==0.0.0.0) (1.14.2)
Requirement already satisfied: scipy in c:\users\berk\anaconda2\lib\site-packages (from solar==0.0.0.0) (0.19.0)
Requirement already satisfied: gpkit in c:\users\berk\dropbox (mit)\mit graduate school\code\gpkit (from solar==0.0.0.0) (0.7.0.0)
Requirement already satisfied: pandas in c:\users\berk\anaconda2\lib\site-packages (from solar==0.0.0.0) (0.17.1)
Requirement already satisfied: gpfit in c:\users\berk\dropbox (mit)\mit graduate school\code\gpfit (from solar==0.0.0.0) (0.1)
Collecting gpkitmodels (from solar==0.0.0.0)
  Could not find a version that satisfies the requirement gpkitmodels (from solar==0.0.0.0) (from versions: )
No matching distribution found for gpkitmodels (from solar==0.0.0.0)
```
This is because the module is no longer called gpkitmodels. Easy fix.

setup.py

@@ -35,7 +35,7 @@
     author="MIT Convex Engineering",
     author_email="[email protected]",
     url="https://www.github.com/convexengineering/solar",
-    install_requires=["numpy", "scipy", "gpkit", "pandas", "gpfit", "gpkitmodels"],
+    install_requires=["numpy", "scipy", "gpkit", "pandas", "gpfit", "gplibrary"],
     version="0.0.0.0",
     packages=["solar"],
     package_data={"solar": ["*.csv"]},