Generalize setvars script for OW compiler
Setup of OW compiler for build process is externalized.
Now it is user responsibility if select OW compiler for build process that setup selected OW compiler (OW version or 32/64-bit binaries) before configure/run build process
update build server after changes in setvars script
remove OW configuration, now it must be done before running build server if OW is used for building
remove OW configuration stuff from build server
Updated BUILD.md to reflect recent changes in setvars. Also added some comments about testing.