add set of completion wrap tokens for bash escape

I've noticed a few more problems in the way that the xonsh parser can
interfere with bash completion (or vice versa).  This adds a set of
tokens that might show up in filenames that cause trouble.  If one of
these tokens is in a filename/path then the bash completer will return
the `repr` of the filename and the xonsh parser won't try to interpret
the special symbols in the filename

xonsh/completer.py

@@ -30,6 +30,8 @@ XONSH_TOKENS = {
 
 COMPLETION_SKIP_TOKENS = {'sudo', 'time'}
 
+COMPLETION_WRAP_TOKENS = {' ',',','[',']','(',')','{','}'}
+
 BASH_COMPLETE_SCRIPT = """source {filename}
 COMP_WORDS=({line})
 COMP_LINE={comp_line}
@@ -318,7 +320,7 @@ class Completer(object):
         space = ' '
         slash = '/'
         rtn = {_normpath(repr(s + (slash if os.path.isdir(s) else '')))
-               if space in s else
+               if (COMPLETION_WRAP_TOKENS.intersection(s) != set()) else
                s + space
                if s[-1:].isalnum() else
                s for s in out.splitlines()}