add url subcommand to post, comment and site commands
add new line to the end of files
replace WP_CLI::print_value() with WP_CLI::line()
fix issues around plugin activation by setting $GLOBALS['pagenow'] to
the expected value

closes #917
Fix wrong example in 'wp comment list' documentation
make url subcommand accept multiple ids
Merge pull request #919 from rodrigoprimo/comment-list-doc

Fix wrong example in 'wp comment list' documentation
Merge pull request #917 from wp-cli/pagenow

Error activating JetPack
Merge pull request #915 from rodrigoprimo/post-url

First pass at url subcommand for post, comment and site commands
make 'wp comment delete' accept multiple IDs
Merge pull request #921 from rodrigoprimo/comment-delete

Make 'wp comment delete' accept multiple IDs