Small fixes for develop.md and Ansible playbooks

* Fixed typo in path in develop.md
* Fixed ca_cert path in *-specific.yml (ca_cert is in ossec_server not mon role)
* Capitalization and readability
* Tested staging on newer Ansible and Vagrant (don't merge until confirm)
Cleanup
Grammar
Vagrant version update due to #802
Slight language adjustment
Merge pull request #801 from ageis/small-fixes

Small fixes