Add WP_DEBUG options to the wordpress app parameters

The original implementation was using a define constant, which meant
that the additional configuration file could not override the pre-set
values from the initial template.

This commit adds:

- WP_DEBUG
- WP_DEBUG_LOG
- WP_DEBUG_DISPLAY

All values default to false, which matches the initial implementation
for WP_DEBUG and continues that intent for the new values.
add more info about how wp_user is created to documentation
fixes #27 - move exec user and group from resource default to individual resources
Merge pull request #44 from GeoffWilliams/classroom-doco-upgrade

add more info about how wp_user is created to documentation
Merge pull request #46 from jantman/issue27

fixes #27 - move exec user and group from resource default to individual resources
Merge pull request #40 from enekogb/master

Use ${wp_lang} as part of the name of the downloaded tar.gz
Merge pull request #42 from DDC-Advocacy/master

Add WP_DEBUG options to the wordpress app parameters
Allow overriding wp-config.php content

The wp_additional_config parameter already exists, but in the case where
the entire config is to be overridden, this parameter may be used.
Merge pull request #48 from hunner/custom_content

Allow overriding wp-config.php content
Ignore some variables' defaults
Merge pull request #49 from hunner/custom_content

Ignore some variables' defaults
Allow multiple wordpress instances

Thanks to @mikegleasonjr for the code!

Closes #29

Also converts rspec-system tests to beaker-rspec tests.
Merge pull request #36 from hunner/multi_instance

Allow multiple wordpress instances
Release 1.0.0
Merge pull request #51 from hunner/release_1.0.0

Release 1.0.0
Multi instance test didn't curl 2nd instance
Merge pull request #52 from hunner/fix_test

Multi instance test didn't curl 2nd instance
Merge pull request #1 from hunner/master

Merged changes from hunner:master