add missing fortran compiler.

.travis.yml

@@ -8,7 +8,7 @@ python:
 #  - "3.2"
 # command to install dependencies
 before_install:
-  - sudo apt-get install -qq libatlas3gf-base libatlas-dev liblapack-dev
+  - sudo apt-get install -qq libatlas3gf-base libatlas-dev liblapack-dev gfortran
 #  - sudo apt-get install -qq libopenblas-dev
 install:
 # If we don't install numpy before SciPy 0.10.1, the SciPy installations fails.