Fix erlexec application name

erlexec now requires that particular name in order to successfully boot.

index/exec.mk

@@ -1,5 +1,5 @@
 PACKAGES += exec
-pkg_exec_name = exec
+pkg_exec_name = erlexec
 pkg_exec_description = Execute and control OS processes from Erlang/OTP.
 pkg_exec_homepage = http://saleyn.github.com/erlexec
 pkg_exec_fetch = git