Set default values for boolean fields on Chant creation

[lucasmarchd01]

Create a new chant in the database. When the chant is saved, the fields for manuscript_full_text_std_proofread, manuscript_full_text_proofread and volpiano_proofread will be NULL:

cantusdb=# SELECT
    id,
    manuscript_full_text_std_proofread,
    manuscript_full_text_proofread,
    volpiano_proofread
FROM main_app_chant
WHERE id = 1005633;
   id    | manuscript_full_text_std_proofread | manuscript_full_text_proofread | volpiano_proofread 
---------+------------------------------------+--------------------------------+--------------------
 1005633 |                                    |                                | 
(1 row)

Edit and save the chant one more time, and only then are default values of False added to these fields:

cantusdb=# SELECT
    id,
    manuscript_full_text_std_proofread,
    manuscript_full_text_proofread,
    volpiano_proofread
FROM main_app_chant
WHERE id = 1005633;
   id    | manuscript_full_text_std_proofread | manuscript_full_text_proofread | volpiano_proofread 
---------+------------------------------------+--------------------------------+--------------------
 1005633 | f                                  | f                              | f
(1 row)

We should have a default value set for these fields when a Chant is initially created. We should also check other fields to make sure it isn't happening elsewhere.