Coala command: use --limit-files

Uses `--limit-files` instead of `--files`.  Also, additional line-start
and line-end regexp patterns.  coafile: Ignore for gitmate CI and
include for ert.

.coafile

@@ -1,8 +1,7 @@
-[Default]
-enabled = True
-
 [commit]
 bears = GitCommitBear
 
 [python]
 bears = PEP8Bear
+files = **.py
+ignore = test/resources/language/*.py

flycheck-coala.el

@@ -34,10 +34,10 @@
 (flycheck-define-checker coala
   "A checker using coala.
 See URL `https://coala.io'."
-  :command ("coala" "--format" "{line}:{column}:{severity_str}:{message}" "--find-config" "--files" source)
-  :error-patterns  ((error (or "None" line) ":" (or "None" column) ":MAJOR:" (message))
-                    (warning (or "None" line) ":" (or "None" column) ":NORMAL:" (message))
-                    (info (or "None" line) ":" (or "None" column) ":INFO:" (message)))
+  :command ("coala" "--format" "{line}:{column}:{severity_str}:{message}" "--find-config" "--limit-files" source-original)
+  :error-patterns  ((error line-start (or "None" line) ":" (or "None" column) ":MAJOR:" (message) line-end)
+                    (warning line-start (or "None" line) ":" (or "None" column) ":NORMAL:" (message) line-end)
+                    (info line-start (or "None" line) ":" (or "None" column) ":INFO:" (message) line-end))
   :modes (c-mode
           csharp-mode
           c++-mode

test/resources/language/.coafile

@@ -0,0 +1,3 @@
+[python]
+bears = PEP8Bear
+files = *.py