Change capability for EDD Add Ons and System Info sub menus

The "install_plugins" capability gives only WP super admins on WP multisite installs access to Add Ons, System Info Upgrade screen.
This is how it should be.
On single WP installs the Admin still can access these sub menus.
see
http://codex.wordpress.org/Roles_and_Capabilities
Update shortcode-receipt.php

Please see https://easydigitaldownloads.com/support/topic/wrong-tax-description-on-checkout-page/
It needs to show (incl. tax) instead of (ex. tax) to make sense.
Merge pull request #1313 from ghost1227/master

Fix for #1309
Merge pull request #1291 from robaggior/patch-2

Change capability for EDD Add Ons and System Info sub menus
Fix duplicate key in unit test. Closes #1302
Fix for #1320
Merge pull request #1312 from robaggior/patch-3

Update shortcode-receipt.php - change tax description to (incl. tax)
Updated Japanese lang files
Merge branch 'master' of github.com:easydigitaldownloads/Easy-Digital-Downloads
Tweak default template CSS for #1327
Revert "Tweak default template CSS for #1327"

This reverts commit 6214853861bdd879d61667452a205c9e1d42e3c6.
Bump up the padding. See #1327.
Add a background and make sure the CSS works with Outlook. Also, change some of the styling of the main wrapper. See #1327.
Improve typography. See #1327.
Double decimals in cart widget. Closes #1323
Reintroduce [download_history]. Refactored the entire template and made it work with bundled files. Closes #1262
Show payment status if not complete. #1262
You're welcome for all the whitespace.
Merge pull request #1328 from JustinSainton/patch-3

You're welcome for all the whitespace.
Show '$0.00' as 'Free'. See #1109.