makefile: Fix make distcheck

make distcheck tries to verify that make dist contains all files needed
to actually install the tarball. We want this to work - also, we want
this to continue working, so let's put it in the travis config.

Signed-off-by: Robin Sonefors <robin.sonefors@op5.com>
build: Create the naemonstats binary

Somewhere along the way, the old nagiostats binary got removed instead
of renamed.

Signed-off-by: Robin Sonefors <robin.sonefors@op5.com>