Merge pull request ethereum#848 from KentShikama/patch-1

Add libyaml-cpp-dev to Ubuntu/Debian installation

Author: joeykrug

README.md

@@ -8,7 +8,7 @@ https://github.com/ethereum/pyethapp
 ## Installation:
 
 ```bash
-sudo apt-get install libssl-dev build-essential automake pkg-config libtool libffi-dev libgmp-dev
+sudo apt-get install libssl-dev build-essential automake pkg-config libtool libffi-dev libgmp-dev libyaml-cpp-dev
 git clone https://github.com/ethereum/pyethereum/
 cd pyethereum
 python setup.py install