Merge pull request #106 from kern3020/master

doc changes: minor tweaks to improve the formatting
Partially implement patch from David M Noriega
(https://github.com/davidmnoriega):

* do not use `-i` option for `sftp` command, as some sftp versions do
  not support it
* use `-o IdentityFile=<file>` instead for `sftp`, that is (probably)
  supported by any version of sftp.
Add documentation for configuration option `network_ids`
ignore autogenerated files
Update to use current ansible version (1.7.2)
Merge pull request from John Morrissey (https://github.com/jwm)
Remove dependency from ansible 1.3.3
Partially implement pull request   https://github.com/gc3-uzh-ch/elasticluster/pull/114 from John Morrissey.
Add tag `Name` to EC2 instances, and use `<cluster.name>-<node.name>` as name for the instance.
Update playbooks to work with Ansible 1.7.2
Fix playbooks for slurm/precise
More bugfix
Fix gluster playbooks
Fix core-site.xml file not correctly parsed by hadoop
Fix more playbooks
Merge branch 'ansible-1.6'
Update playbooks to work with ansible 1.7
remove ansible verison from instructions, pull request instructions (branching) fixes #119
fix failed test caused by more verbose node name
accept all changes from upstream/master