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/hdf5-blosc/package.py

@@ -184,7 +184,7 @@ def check_install(self, spec):
                "-L%s" % spec["hdf5"].prefix.lib, "-lhdf5")
             try:
                 check = Executable("./check")
-                output = check(return_output=True)
+                output = check(output=str)
             except:
                 output = ""
             success = output == expected

var/spack/repos/builtin/packages/hdf5/package.py

@@ -263,7 +263,7 @@ def check_install(self):
                  spec['hdf5'].libs.ld_flags.split()))
             try:
                 check = Executable('./check')
-                output = check(return_output=True)
+                output = check(output=str)
             except:
                 output = ""
             success = output == expected

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