New default bank holidays

Update set of default Bank holidays for new year

Attempt to fix accumulating of open LDAP connections

If company has LDAP authentication enabled, connections are keep accumulating over the time.
This version attempts to fix the issue.

Prevent leave request submission if the type is not selected

• Prevent leave request submission if the type is not selected
• Update tests for new year

Config option to enforce users to explicitly choose leave type when booking time off

Some organisations require employees to explicitly pick the type of leave when booking time off. So employee makes a choice rather than relying on default settings. That reduces number of "mistaken" leaves, which are cancelled after.

A Leave Type can be auto approved

Allow to configure auto approved Leave Types: leave of that type would not need to obtain supervisor's approval.

Big thanks to @fery for submitting Pull Request.

Screenshot

Introduce Redis as alternative session storage.

Add alternative storage for sessions: Redis.

See docs for details how to configure it.

Prevent double submission from browser

Introduce mechanism to prevent double submission so browser avoids sending form payload twice.

Fix issue with Leaves report

Fix issue with Leave report: now it renders any leaves that overlap with provided date range, not only those start and end within the period.

Store Team View's department ID in session

UX improvement so Team View filter settings stay intact between page's visits.

UX improvements for the Team View page

Few UX improvements for the Team View page

• New labels align in style with existing ones throughout application
• Store newly introduced grouped_mode parameter in the session so it is saved between pages
• Fix filtering when grouped_mode and department_id are selected