fix complaints in Diagnostics when no migrations has been run

[ildyria]

Fixes complaint seen in #1988

Output of the diagnostics [REQUIRED]

/crashplan/www/lychee# php artisan lychee:diagnostics

In Connection.php line 795:

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'may_administrate' in 'where clause' (Connection: mysql, >SQL: select count(*) as aggregate
from users where may_administrate = 1)

In Connection.php line 416:

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'may_administrate' in 'where clause'

Basically skip any check that requires a DB interaction.

[codecov]

Codecov Report

Merging #1990 (af2c583) into master (12bd6d4) will increase coverage by 1.82%.
The diff coverage is 50.00%.

Additional details and impacted files