Naming cleanup

closes #4069
- Rename everything from camelCase to lowercase + dashes
- Remove usage of `server`, `app` and `instance`
Validate and properly color letter count.

fixes #4087
- Adds correct validations for meta_title/meta_description
- Adds correct coloring of letter count
Show all authors in post settings menu

Closes #4016
- Added 'limit=all' to API query to retrieve all users.
Merge pull request #4074 from halfdan/4069-rename

Naming cleanup
Add checks for packages and contentPath to startup

Refs #3864
- Make sure that require() is able to resolve all dependencies
  listed in package.json.  If packages are missing halt the
  bootstrap process and display an error and help message for user.
- Check that contentPath and its subdirectories exist with the correct
  permissions.
- Check sqlite3 database file is set for read/write access.
Merge pull request #4094 from frantzypants/issue-4016

Show all authors in post settings menu
Merge pull request #4089 from halfdan/4087-meta

Validate and properly color letter count.
Merge pull request #3913 from jaswilli/require-errors

Add checks for packages and contentPath to startup
More robust deprecation check code

Closes #4082
* reformatted code to allow for traversal
* deeper config items should be denoted like this: `object.object.object.property`.
* added tests for testing the deprecation warnings
Deprecated mail.fromaddress, mail.from is Title <email@address>

Closes #4018

* cleaned up `mail_spec.js`
* deprecated `mail.fromaddress`
* implemented 'Blog title <email@address.com>' format with fallbacks
* added tests to deprecation and from address, made existing ones more robust
* moved domain intuit into its own module: `GhostMailer.getDomain()`