Split donor creation form into two step process (See #47) T:9h00

Added Add Donor Section to 'Find Donors' tab, to work with the
following workflow:

- Before adding new donor, search for donor to see if they exist in
current system.
- If they do not exist, enter in donor info in short 'Add Donor' form
on 'Find Donors' tab that consists of all mandatory fields, as well as
Notes field.
- Once donor has been created, option to update donor details or
continue and update at a later stage.
Uncaught TypeError: Cannot read property 'top' of undefined (T:4h00)
Remove console output used for debugging (T:0h05)
Add mandatory fields in Add Donor form (See #14) T:0h30
Default Gender choice should be empty/null (See #48) T:0h20
Remove Age from Add Donor form (See #12) T:0h20
Ensure Donor Code is not editable (See #6) T:0h30
Add Checkbox Field for DOB 'Estimated' (See #13) T:4h00
Merge pull request #50 from jembi/app_area_donors

Appl. area - Donors