Tighten ERROR regexp in log checker

Because each project uses a slightly different format for logging, and
sometimes different formats within a project, it is hard to match ERROR as
the log level across all log files. There was a failure caused by "ERROR"
actually showing up inside a keystone token. This change will prevent that
though it is still possible something else could slip through.

Change-Id: Ic8b036b4ed7481856231b2d073d273b1df783415
diff --git a/tools/check_logs.py b/tools/check_logs.py
index 6d4436e..f5b46b5 100755
--- a/tools/check_logs.py
+++ b/tools/check_logs.py
@@ -31,7 +31,7 @@
 
 
 def process_files(file_specs, url_specs, whitelists):
-    regexp = re.compile(r"^.*(ERROR|CRITICAL).*\[.*\-.*\]")
+    regexp = re.compile(r"^.* (ERROR|CRITICAL) .*\[.*\-.*\]")
     had_errors = False
     for (name, filename) in file_specs:
         whitelist = whitelists.get(name, [])