[ADDED] Notification cleanup script

* [ADDED] Admin Panel Setting for max age for notifications
* [ADDED] Cronjob to clean out old notifications
* [ADDED] New cron to scripts and monitoring

Fixes #1672 once merged.
[UPDATE] Added INDEX to transactions table

Should speed up queries using both account_id and archived for a
specific account.
Merge pull request #1751 from MPOS/transaction-index

[UPDATE] Added INDEX to transactions table
[FIX] Correcting user ID for new block emails

Also adding the currency to the notifications as well.
Merge pull request #1753 from andymornes/next

[FIX] Correcting user ID for new block emails
Merge pull request #1739 from MPOS/notification-cleanup

[ADDED] Notification cleanup script
[FIX] Added missing file, gitignore :/
Merge branch 'next' of github.com:MPOS/php-mpos into next
[FIX] PPS Payout processing

* [ADDED] Abort if we don't have enough shares to calculate PPS from
* [FIXED] Proper calculations for account shares, we dropped a share
  each run
* [ADDED] Error code if no new shares available
[UPDATE] ACL Management

* [ADDED] Smarty acl_check function
* [ADDED] Optional default return  value for getValue calls
* [UPDATE] ACL Checks in page controllers
* [UPDATE] Navigation template to use check_acl from Smarty
* [ADDED] New ACL options where needed
* [REMOVED] Disable pages from System Settings Tab
* [ADDED] Above removed pages into ACL Settings Tab

This will make usage of ACLs a bit easier and transparent.
Also fixes #1731 once merged.
Merge pull request #1738 from MPOS/acl-overhaul

[UPDATE] ACL Management
[REMOVED] Liquid Payout cron due to issues

Payouts did not work very well and caused more issues for pools than
being worth having this cron. We revert this and let them use
sendtoaddress again whenever they wish to deduct payouts from their pool
at their own discretion.

We may add this thing back in sometime later with a proper and working
implementation but no promises.
[REMOVED] Liquid payout cron from monitoring pages