make: dh: Command not found

The guy in IRC was almost there, but not quite. The package that you need is called dh-make no devscripts. A simple sudo apt-get install dh-make should fix the issue.

How to know:

chmod 744 debian/pxpress/switch*
dh build
make: dh: Command not found
make: *** [build-arch] Error 127
dpkg-buildpackage: error: debian/rules build gave error exit status 2

dh build starts creating a debian package with the debhelper scripts, all these scripts are appended with the dh_ string. In this case, dh called a helper called dh_make to build the debian package.

Another cue you have is this line:

dpkg-checkbuilddeps: Unmet build dependencies: debhelper (>= 7) dh-modaliases execstack

You need debhelper, dh-modaliases and execstack to build the package. debhelper suggests dh-make, and suggestions are normally installed.