Minor enhancement to be able to specify the number of seconds before
timeout the connection, default is set to 10 seconds.
Minor improvement to retry the HTTP request up to three times in case
an exception is raised during the connection to the target url.
Minor bug fix to correctly catch connection exceptions and notify to
the user also if they occur within a thread.
Minor code restyling.
Updated documentation.
implemented Time based blind SQL injection now is a single test file
within the lib/techniques/ folder.
Renamed lib/techniques/inference to lib/techniques/blind, it is more
approriate and adapted the rest of the libraries.
Updated ChangeLog file.
