[BZ 1148186] Use eval to execute the RHQ agent start command. It was incorrectly sourced in the current script. Note that only config and full config were affected. Also, adjusted the order for defining and export RHQ home to allow proper overrides int RHQ environment script.

(cherry picked from commit d583b234429ca466e3e067dc02635394f711a8fd)
Signed-off-by: Thomas Segismont <tsegismo@redhat.com>
[BZ 1148186] More updates for the initial commit:
1) Only assign the pwd to RHQ_AGENT_HOME not already defined
2) Use a temp variable to extract pwd before dirname

(cherry picked from commit ca21dac99551fbb62d33db7e66b154857a96a68c)
Signed-off-by: Thomas Segismont <tsegismo@redhat.com>
[BZ 1148186] One more update to the initial commit:

- Switch to use $_DOLLARZERO variable to correctly identify the location of the script.

(cherry picked from commit 1df956d314083e10660c173cbfd562778e4f16b5)
Signed-off-by: Thomas Segismont <tsegismo@redhat.com>