Clarify Python 2 use. Remove OpenBLAS instructions.
# Pre-requisites
-## Python
+## Python 2
### Misc
```
```
# apt install liblapack-dev libatlas-dev
-# pip install scipy
-```
-
-#### OpenBLAS?
-```
-$ ck install package:lib-openblas-0.2.20-universal
-$ ck search env --tags=openblas,v0.2.20
-$ ck load env:<...>
-$ cd $INSTALL_DIR/src
-$ sudo PREFIX=/usr/local make install
+# pip2 install scipy
```
## Install via CK
