Introducing Python based Test Environment

Squashed Commit, of the following commits:

7743384 Update documentation to reflect changes in code
b703633 Add feature that allows to ensure that Wget correctly crawls the website in recursive mode
0758f47 Add new test for recursive spider mode
43bb61b Smartly guess content type header
d4d0e63 Support substring replace in File Contents too
f578500 Compatibility fix with multiple servers
8b1a9b6 Extend Functionality to support spawning multiple servers
e84192a Use the provided calls to shutdown server instead of rewriting it
99659f3 Improve Documentation
cb94e52 Slight code cleanup. Remove unused code
886ac1a Shift to new Threading Model from Multiprocessing model
e74c2ec Add new test for POST Requests
48644f1 Print diff when file contents don't match
b6f9efe Add tests for Cookie support
4c9e6b4 Document pending work
e13bc90 Add new test to ensure Content Disposition and Auth work together
60d1f4d Add new Test for Continue command
738b299 Add test, Test-Head
9b9d16b Edit non-unique TEST_NAME variable
ae958db Minor optimizations to the way Server Rules are executed
50b4f0c The rules need not be a defaultdict.
dccc154 Introducing Python based Test Environment
testenv: fix make dist
testenv: Remove Test--spider-r.py from XFAIL_TESTS
More features to Python based test suite

Squashed Commit from parallel-wget of:
b31e6e4 Add support for HTTPS Servers
b828a6e Sleep for n seconds before calling Wget Executable
7effa90 Support programatically setting Handler class variables
7e1f4c1 Correct the call to stop_HTTP_Server
f616192 Improve error handling when wget executable isn't available
31868fe Split large function to improve readability and extensibility
Refactor the Python based test suite

This is a squashed commit of the following from parallel-wget:
ecd6977 Refactor mainly the test cases classes
d26c8eb Create package test for test case classes
507383d Move server classes to package server.protocol
195393b Create package conf where rules and hooks are put
42e482a Create package exc and move TestFailed to exc
82f44f3 Fix a typo in Test-Proto.py
31e5f33 From WgetTest.py move WgetFile to misc
422171d Create package misc, move ColourTerm.py to misc
Fix crash in test suite
Document SERVER_WAIT
Support running tests through valgrind