BUGFIXES to DBInterface:
- Correct issues with is_int vs. is_numeric when validating params.
- Use correct prepared statement when inserting record in
createLoginSession
- Lookup employee type instance by name when reading existing Rank
record
- Was not passing $activeFlag parameter into Employee constructor

BUGFIX to Department: Correct issues with is_int vs. is_numeric when
validating params.

BUGFIX to Employee:
- Correct issues with is_int vs. is_numeric when validating params.
- Implement boolean parsing/interpretation for $activeFlag property

EmployeeType: Added static method fromName for looking up instance by
enumeration name from database

LoginSession: Added convenience method getIsAdministrator (for
isAdministrator property)

BUGFIX to Rank: Correct issues with is_int vs. is_numeric when
validating params.

BUGFIX to TaxRate: Correct issues with is_int vs. is_numeric when
validating params.

Renamed clogin.php to doLogin.php, and updated to return JSON response
for use via AJAX request.

Updated "commpn.php":
- New defines: HTTPS, SERVER_URL, BASE_URL
- Automatically creates $db variable containing DBInterface instance
- Added functions: doUnauthorizedRedirect(), getLoginRedirect(), and
doLoginRedirect()

Updated "index.php":
- Check if valid session exists, and redirect to appropriate landing
page if it does.
- Added form validation, and perform login via AJAX request.
- Display spinner image while authentication is performed.

Updated "u_payDB.sql":
- Ensure admin employee/user is defined with a non-empty address and
taxID.
- Defined a new employee "brad" which is not an administator.