Switch logger for debug

Instead of using our internal "logger", switch to using the debug
package.  Include additional debug messages where appropriate.  Remove
the "logger" library and test.
Configurable HTTP headers and retryStatusCodes

Allow the HTTP headers and retry status codes (within the page scrape
function) to be configurable.
Add retrySleepTime, allow configurable

Add a sleep time between retries, and allow this time to be
configurable.  Default to 1000ms (1 second).
Update readme

Include information on the new configuration options, and changes to
debug.
Update readme

Remove whitespace from code
Update dependencies, bump version

Update the dependencies to the latest, bump the version based on
changes made so far.