added API for accessing scan configuration for proxy scanner
Don't force display of debug output to 'true'
Synchronize scanner debug preferences with proxy scan configuration when proxy scan enabled/disabled
Perform extra validation of host argument
Verify that host data extracted from scraped URI is legit
Make our custom request wrappers 'abortable'
Specify if response entity should be fully read in advance

The only case in which we don't want to read the entire entity at once
is in the proxy where large responses should be streamed to the browser.
Use custom internal request type for PUT request