Bug 16525: Have cancel button when adding new aq budget

Bug 16525: Have cancel button when adding new aq budget

At the moment you only see the cancel button on the form if editing an
existing budget. This patch adds a cancel button to the form which adds
a budget. Also changes the wording of the save button from 'Save
changes' to just 'Save' so it makes more sense when adding a new budget

To test:
1) Go to Admin -> Budgets -> New budget
2) Notice 'Save changes' button and no cancel
3) Apply patch and refresh page
4) Notice 'Save' button and 'cancel' link
5) Click 'cancel' - should be taken to Budgets administration page
6) Edit an existing budget
7) Click 'cancel' - should be taken to the funds page for that budget

Sponsored-by: Catalyst IT
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Sabine Liebmann <Liebmann@dipf.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Still an issue: If edit a budget fron aqbudgets.pl, then cancel, you get
aqbudgets.pl?budget_period_id=XX. But existed before this patch.

Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>