shill: Fix most of warnings from cpplint

Fix most cpplinter's warnings. On a few occasisions, the warnings
produced were false-positives, so added explicit // NOLINT comment
overrides.

There were a few instances of disallowed non-const reference usage
(reported as runtime/reference error by cpplint) for
"DBus::Error &error" which should potentially be changed
to pointers to comply with C++ coding style but I will let Shill
owners do that since there is quite a few of those and the
change isn't brain-dead simple...

BUG=None
TEST=platform2 still compiles and all unit tests pass.

Change-Id: Ic2e31896aa13d20eeb1a85dee74f3db8cccfde2e
Reviewed-on: https://chromium-review.googlesource.com/204164
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/resolver_unittest.cc b/resolver_unittest.cc
index 5a5dbdc..f7b1449 100644
--- a/resolver_unittest.cc
+++ b/resolver_unittest.cc
@@ -35,7 +35,7 @@
   "nameserver 8.8.9.9\n"
   "search google.com\n"
   "options single-request timeout:1 attempts:5\n";
-}  // namespace {}
+}  // namespace
 
 class ResolverTest : public Test {
  public: