.travis.yml: Replace the system `libpython2.7.so` with the one included in our environment.
.travis.yml: Replace the system `libpython2.7.so` with the one included in our environment.

CellProfiler/python-javabridge,jakirkham/python-javabridge,jakirkham/python-javabridge,CellProfiler/python-javabridge,CellProfiler/python-javabridge,CellProfiler/python-javabridge,jakirkham/python-javabridge,jakirkham/python-javabridge