URL hacking to easily transform production to local

See #1232
fix blank response for wp comment list --format-ids
adding functional tests
Merge pull request #1406 from wp-cli/fix-comment-list-format-ids

Fix blank response for wp comment list --format-ids
Force https when accessing WordPress.org

WordPress.org started redirecting to https anyway. Sometimes WordPress.org APIs return http though.
Merge pull request #1409 from wp-cli/force-https-wordpress

Force https when accessing WordPress.org
add --activate param to `wp core language install --activate`
add en_US to the list of languages
make it possible to activate en_US language
Add functionality to filter list of languages
add missing new line at end of file
remove empty line added by mistake
improve test for `wp core language --<field>=<value>`
remove underscores from methods names
Wrap `new DateTime` with try{ } catch() {}

It can trigger an Exception if `date.timezone` isn't set
Merge pull request #1422 from wp-cli/try-datetime

Wrap `new DateTime` with try{ } catch() {}
WPorg API returns names with HTML entities. We can decode for CLI.
PHP magic methods, except `__invoke()`, aren't valid WP-CLI commands

PHP reserves `__` prefix for magic methods. Don't use function names starting with `__` unless you're using magic methods.
Merge pull request #1435 from wp-cli/fix-1435

Unencode plugin names when installing
Limit `wp core language list` output by fields