Description of problem:
I tried to run the example Spark job from https://github.com/openstack/sahara/tree/master/etc/edp-examples and got the error

2015-01-21 14:03:55.102 22730 ERROR sahara.service.edp.job_manager [-] Can't run job execution 'a49eba00-d13e-4a06-a37f-cfee3d200925' (reason: [Errno 2] No such file or directory: '/usr/lib/python2.7/site-package
s/sahara/service/edp/resources/launch_command.py')
2015-01-21 14:03:55.102 22730 TRACE sahara.service.edp.job_manager Traceback (most recent call last):
2015-01-21 14:03:55.102 22730 TRACE sahara.service.edp.job_manager   File "/usr/lib/python2.7/site-packages/sahara/service/edp/job_manager.py", line 118, in run_job
2015-01-21 14:03:55.102 22730 TRACE sahara.service.edp.job_manager     _run_job(job_execution_id)
2015-01-21 14:03:55.102 22730 TRACE sahara.service.edp.job_manager   File "/usr/lib/python2.7/site-packages/sahara/service/edp/job_manager.py", line 99, in _run_job
2015-01-21 14:03:55.102 22730 TRACE sahara.service.edp.job_manager     jid, status, extra = eng.run_job(job_execution)
2015-01-21 14:03:55.102 22730 TRACE sahara.service.edp.job_manager   File "/usr/lib/python2.7/site-packages/sahara/service/edp/spark/engine.py", line 174, in run_job
2015-01-21 14:03:55.102 22730 TRACE sahara.service.edp.job_manager     r.write_file_to(launch, self._job_script())
2015-01-21 14:03:55.102 22730 TRACE sahara.service.edp.job_manager   File "/usr/lib/python2.7/site-packages/sahara/service/edp/spark/engine.py", line 111, in _job_script
2015-01-21 14:03:55.102 22730 TRACE sahara.service.edp.job_manager     return files.get_file_text(path)
2015-01-21 14:03:55.102 22730 TRACE sahara.service.edp.job_manager   File "/usr/lib/python2.7/site-packages/sahara/utils/files.py", line 24, in get_file_text
2015-01-21 14:03:55.102 22730 TRACE sahara.service.edp.job_manager     return open(full_name).read()
2015-01-21 14:03:55.102 22730 TRACE sahara.service.edp.job_manager IOError: [Errno 2] No such file or directory: '/usr/lib/python2.7/site-packages/sahara/service/edp/resources/launch_command.py'


Version-Release number of selected component (if applicable):
openstack-sahara.noarch 2014.2.1-2.el7.centos
python-saharaclient.noarch 0.7.6-1.el7.centos


Steps to Reproduce:
1. Setup a Spark cluster with 1 namenode / master and 3 datanodes / slaves.
2. Run Spark examples from https://github.com/openstack/sahara/tree/master/etc/edp-examples