Prefer vim to vi for default editor (#4230)

* vim > vi
* Allow which to accept multiple args
* Update __init__ to use which with multiple args
* Fix doc tests

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

@@ -72,7 +72,7 @@ def setup_environment(self, spack_env, run_env):
         # spack_env.set('JAVA_HOME', self.spec['jdk'].prefix)
 
         hadoop = self.spec['hadoop'].command
-        hadoop_classpath = hadoop('classpath', return_output=True)
+        hadoop_classpath = hadoop('classpath', output=str)
 
         # Remove whitespaces, as they can compromise syntax in
         # module files