Remove URI filter for parenthesis and dollar symbols, as talked in #47.

Signed-off-by: Razican <admin@razican.com>
Fixed return.

Signed-off-by: Razican <admin@razican.com>
Fixed tests

Signed-off-by: Razican <admin@razican.com>
Fixed sub-section header

Signed-off-by: Hans Anderson <me@hansanderson.com>
Merge pull request #3392 from ha17/fix-contributing-section-header

Fixed sub-section header
Merge pull request #3323 from Razican/remove-uri-filter

Remove conversion of 'programmatic characters' to HTML entities in CI_URI::filter_uri()

Close #47
Further changes related to issue #47, PR #3323

 - Removed a test that was created specifically for the 'convert programmatic characters to entities' feature.
 - Changed filter_uri() to accept by reference and to not return anything as its only purpose now is to trigger a show_error() call.
 - Added changelog messages and updated the upgrade instructions.
Fix a filter_uri() test