Test List Vaults functionality
Rework test. Remove commented out tests
feat: block reference counting

This patch prevents deleting of a block from a vault if the block has
files referring to it. It adds a ConstraintError that is thrown if this
is attempted.
fix: config.ini

we can now do 'pecan serve ini/config.py'
the fully qualified path to config.ini must now
be set in config.py
fix: add absolute path check for .ini
Merge pull request #114 from painterjd/feat_no_delete_block_with_refs

feat: block reference counting
pep8 fix
chore: misc formatting, comment fixes
feat: x-object-reference-count header

This patch adds the x-object-reference-count header to block GET
operations, telling the client how many references to this block exist.
Remove skip statement
49_delete_file: Fix bug of response code
Merge pull request #122 from raxyu/49_delete_file

49_delete_file: Fix bug of response code
Merge pull request #123 from jc7998/delete_files

Remove skip statement for Delete File Test
Tests/support for block reference count
Merge pull request #118 from TheSriram/fix_ini

fix: config.ini
Merge branch 'master' into list_vaults2
Merge pull request #110 from jc7998/list_vaults2

Test List Vaults
Remove skip statement
Merge pull request #121 from painterjd/mix_cleanup

feat: x-object-reference-count header
rm: vestigial six.PY3 reference