Added u-blox test repository

Also, allow a repository to synchronize with more than one source
directory.
Changed u-blox modem test

The test is not automated now, so it can be synced with the official
repository.
Also changed it to look more like the original VodafoneUSBModem test by
adding another thread in the code.
Fixed macro definitions in u-blox test
Added macro definition from command line

build_api.py now support macros defined at compile time, so build.py and
make.py can be used like this:

$ make.py/build.py <options> -DMACRO1 -DMACRO2=VALUE2 ...