Add add_sb_package(...) call for ncurses
Disable building wget by default

Primarily because the version build by uvcdat is old and does not build
on newer systems because of missing openss v2 (v3 is the latest)
The Qt package variable is qt4_pkg not qt_pkg
Reorder package includes

No configure time dependency managment is performed so the order
of include needs to be correct.
SB_ENABLE_SYSTEM_{uc_package_name} => SB_ENABLE_{uc_package_name}

There should only be a single entry for each package with a
value of ON OFF or SYSTEM. This must be left over from previous
version.
Add --sip switch if SB_ENABLE_SIP is ON

SB_BUILD_SIP is no longer used. Instead check for SB_ENABLE_SIP
have value equal to 'ON'.