Settings: N poring combine

Settings: tethering & portable hotspot help
merge b721eb5ad037d41cc95883d01d24f8aa26646e49

Settings: Move all carrier specific requirements to extension and these function
merge 05059c4938cd30e23fdaf91cbb02b0f65e0f3971

Settings: add USB tethering to USB connection type
merge 05c5422586495ff49126e2d91a250abe7fd0ee9a

Change-Id: I4ef17691f1aed44a47f38ca950fe6300d1687dcd
CRs-Fixed: 1039263