DB: increase default history num

git-svn-id: https://plugins.svn.wordpress.org/feedly-insight/trunk@853576 b8457f37-d9ea-0310-8a92-e5e31aec5664
code optimize

git-svn-id: https://plugins.svn.wordpress.org/feedly-insight/trunk@853577 b8457f37-d9ea-0310-8a92-e5e31aec5664
code format

git-svn-id: https://plugins.svn.wordpress.org/feedly-insight/trunk@853579 b8457f37-d9ea-0310-8a92-e5e31aec5664
add sub menu in admin/index

add option
replace some variable to option

git-svn-id: https://plugins.svn.wordpress.org/feedly-insight/trunk@853580 b8457f37-d9ea-0310-8a92-e5e31aec5664
add feedly button shortcode

git-svn-id: https://plugins.svn.wordpress.org/feedly-insight/trunk@853581 b8457f37-d9ea-0310-8a92-e5e31aec5664