Fixes various compiler diagnostics

Found with LLVM 3.9.1 and then fixed the most severe categories.

src/server/api/parameters_parser.cpp

@@ -55,7 +55,7 @@ boost::optional<ParameterT> parseParameters(std::string::iterator &iter,
         // iterator to the failing position. Extract the position from the exception ourselves.
         iter = failure.first;
     }
-    catch (const boost::numeric::bad_numeric_cast &e)
+    catch (const boost::numeric::bad_numeric_cast &)
     {
         // this can happen if we get bad numeric values in the request, just handle
         // as normal parser error