[SIMB-1824, SIMB-1827] easycwmp: replace characters that will cause t…

[SIMB-1824, SIMB-1827] easycwmp: replace characters that will cause trouble with URIs

Not everything will URL-encode correctly, and this can play very
badly with some ACS servers, e.g., on firmware filenames.  So,
replace with "_" any characters that are too weird to allow through
on IDs, names, labels and URIs.

Add an openwrt-style patch with a possible fix.

Upstream: http://support.easycwmp.org/view.php?id=302