Adds scaffolding for child theme (based on Twenty Twelve by default)

Apart from creating an empty underscore theme, it would be cool to be
able to create an empty child theme. I've implemented a very basic
command for this. It created a theme folder and style.css which imports
parent theme's styles
Added `post get` command.
add --defaults-file=/dev/null to mysql commands
use run_mysql_query() in functional tests too
Removed the <filename> argument from `post get`.
tests: add IF NOT EXISTS to create_db()
Merge pull request #379 from wp-cli/ignore-db-defaults

Fixes #377
be more explicit about which code is covered by the MIT license
Correct file permissions to 755
Revert a134ce6e46561e9f36ee5efeb33e69ad97b97141

See https://github.com/wp-cli/wp-cli/commit/a134ce6e46561e9f36ee5efeb33e69ad97b97141#commitcomment-3001898
Support for `--format` when using `wp post list`
Fix example for 'core is-installed'
Added the `--feature` option for `post get`.
Merge pull request #387 from twisty/master

Example in man page for 'core is-installed' doesn't work
Merge pull request #386 from wp-cli/post-list-format

Support for `--format` when using `wp post list`
Removed CSV format from `post get`, with JSON format it is redundent, etc.
Removed the `post_content` field from the table format output as the table becomes unweildy and the extremely long value of the content or the content itself causes problems with the table processing. Besides, chances are if one wanted the contents and the other fields JSON would be easier anyway.
move iterators to separate namespace
on OS X, wc -l inexplicably outputs whitespace before the result
add smoke test for search-replace
fix class reference in Iterators/Table.php