New features

Added Safety data sheets:
- ChemicalHazard (flammable, toxic, etc.) and Chemical objects should be added in the Detailed administration
- Chemical document can be either uploaded to NEMO or set with a URL
- Common hazard icons are available in the resources folder
- Keywords/synonyms can be set for a Chemical and search through in the Safety data sheet page
- There is no direct link in the navigation bar. A Landing page choice option needs to be added for this with url /safety_data_sheets/. An SDS icon is available for download in the resources folder
Added a button in the calendar to only display qualified tools for non-staff users. This feature is disabled by default and needs to be activated in the Customization page. Thx @pdessauw and NIST MML for the contribution!

Improvements

Updated style of Rate table in Tool control. The table is collapsed by default and can be expanded by default by checking the box in Customization -> Rates
Added LDAP "username_format" property to allow for custom formatting of the username
Checks during login are now case insensitive for username
Added Staff absence note which will only be visible to facility managers
Non-working days will not be shown as absence on the facility manager view of staff status
Updated display of comments in Tool control to keep new lines

Fixed a bug preventing rates from being loaded at startup
Fixed a bug when running migrate of makemigrations before database is initialized
Fixed a bug when authentication fails and is not sending to the correct page due to not allowing POST
Fixed interlock configuration not accepting 0 as coil number
Fixed an issue where all tools would disappear when expanding/collapsing categories and switching from Calendar to Tool control
Fixed a ClosureTime warning on the staff status page
Fixed validation for reservation questions not being updated when adding/removing a group question