Caffe (#3948)

* Added a package for the MDAnalysis toolkit.

* Added the hash for the 1.0 release of caffe and put in a conflict
statemet indicating that protobuf requires a c++11 compiler.

* Changed minimum version number.

* Tweaked the minimum version number.

* Fixed flake8 error.

var/spack/repos/builtin/packages/protobuf/package.py

@@ -41,6 +41,8 @@ class Protobuf(AutotoolsPackage):
     depends_on('libtool',  type='build')
     depends_on('m4',       type='build')
 
+    conflicts('%gcc@:4.6')  # Requires c++11
+
     variant('shared', default=True, description='Build shared libraries.')
 
     def configure_args(self):