editor: use shell to launch editor to allow spaces in editor command

If I want to set a filetype in vim on opening the journla, e.g.:

  vim -c 'set ft=notes' -c Goyo -f

the set and ft=notes will be split and interpreted as two files in vim.
Using the shell to execute the command makes it possible to have editor
commands with quoted/escaped spaces in them.

jrnl/util.py

@@ -130,7 +130,7 @@ def get_text_from_editor(config, template=""):
     with codecs.open(tmpfile, 'w', "utf-8") as f:
         if template:
             f.write(template)
-    subprocess.call(config['editor'].split() + [tmpfile])
+    subprocess.call(config['editor'] + " " + tmpfile, shell = True)
     with codecs.open(tmpfile, "r", "utf-8") as f:
         raw = f.read()
     os.remove(tmpfile)