Add is_store_notice_showing Conditional

Added public is_store_notice_showing conditional to `includes/wc-conditional-functions.php`
Replaced two instances of  `get_option( 'woocommerce_demo_store' )` with the new conditional
Cache tax rates to save database queries
Merge branch 'master' into cached_tax_rates
fixed hard code string, fixes #4489
fixed the indentation in includes/admin/class-wc-admin-dashboard.php
fixed coding standards in includes/admin/class-wc-admin-dashboard.php
fixed the inventory settings install, fixes #4495
fixed the indentation in includes/class-wc-install.php
fixed wordpress coding standards in includes/class-wc-install.php
fixed a small typo in includes/class-wc-install.php
Cleanup sessions - CONCAT is too slow.

Being tested in https://woothemes.zendesk.com/agent/#/tickets/133706
Merge pull request #4485 from pmgarman/store-notice-conditional

Add is_store_notice_showing Conditional
Merge pull request #4490 from claudiosmweb/fix_4489

Fix #4489
Merge pull request #4488 from GeertDD/cached_tax_rates

Cached tax rates
Merge pull request #4496 from claudiosmweb/fix_4495

Suggestion to fix the issue #4495
Missing updated class
Check we have a product #4487
decompress #4501
Customisable names for radios and checkboxes Closes #4493
Input styling fixes