Use uwsgi binary from path

All these uwsgi invocations assume that the uwsgi binary is in the
same directory as their project binaries are installed into (probably
/usr/bin).  That may not be correct -- for example if using a packaged
uwsgi on Fedora the binary will live in /usr/sbin/uwsgi (not /usr/bin
where the project files from pip are).

Switch invocations to just find it in the path.

Change-Id: I298e3374e9c84e209ffcabbaaacda17f8df19f4f
7 files changed