ipalib.cli: Add filename argument to ipa console

This allows writing simple IPA scripts using the shebang
    #! /usr/bin/ipa console

https://fedorahosted.org/freeipa/ticket/4351

Reviewed-By: Nathaniel McCallum <npmccallum@redhat.com>

ipalib/cli.py

@@ -30,6 +30,7 @@ import fcntl
 import termios
 import struct
 import base64
+import traceback
 try:
     #pylint: disable=F0401
     import default_encoding_utf8
@@ -875,14 +876,32 @@ class show_mappings(frontend.Command):
 
 
 class console(frontend.Command):
-    """Start the IPA interactive Python console."""
+    """Start the IPA interactive Python console, or run a script.
 
+    An IPA API object is initialized and made available
+    in the `api` global variable.
+    """
+
+    takes_args = ('filename?',)
     has_output = tuple()
 
-    def run(self, **options):
+    def run(self, filename=None, **options):
+        local = dict(api=self.api)
+        if filename:
+            try:
+                script = open(filename)
+            except IOError as e:
+                exit("%s: %s" % (e.filename, e.strerror))
+            try:
+                with script:
+                    exec(script, globals(), local)
+            except:
+                traceback.print_exc()
+                exit(1)
+        else:
             code.interact(
                 '(Custom IPA interactive Python console)',
-            local=dict(api=self.api)
+                local=local
             )