Add query string pagination functionality

Signed-off-by: kenjis <kenji.uui@gmail.com>
Add functionality pagination url using {page}, fix get() may return incorrect value.

Signed-off-by: Kenji Suzuki <kenji.uui@gmail.com>
Change implementation to use uri_segment and add pagination_url auto detection

Signed-off-by: Kenji Suzuki <kenji.uui@gmail.com>
Remove intermediate variable and switch, fix pagination_url auto detection

Signed-off-by: Kenji Suzuki <kenji.uui@gmail.com>
Fix coding style

Signed-off-by: Kenji Suzuki <kenji.uui@gmail.com>
Add flip() method to the image class

Allow vertical and / or horizontal image flipping.
Merge pull request #1193 from kenjis/add_query_string_pagination

Add query string pagination functionality
reverted the pagination PR. Broke all applications big time!
fixed broken pagination class
Image Class: load(), save(), reload(), load() bug.

Fixes #1225

I'm not sure if this is the best way of going about this,
or if the default image config "persistence" should be set to true
to prevent the second load, but here's one way of skinning the cat.
Fixed config::save() for non-php extensions
Make Config::save() more consistent with Config::load(). Closes #1229
Debug::dump(): encode string variables
Fixes #1230: Added and_on and or_on for Database joins.
refactored Sessions. closes #678, closes #679

Moved validation server side, made encryption optional.
Merge pull request #1228 from lukearmstrong/patch-3

Image Class: load(), save(), reload(), load() bug.
Update tests for Pagination

Signed-off-by: Kenji Suzuki <kenji.uui@gmail.com>
Added missing DB::error_info() method. See fuel/docs#469
Merge pull request #1232 from kenjis/update_pagination_tests

Update tests for Pagination
Remove channels exception in GD driver for Image class

This exception was introduced to fix an issue in this commit
e8751dc by @quetzyg

It didn't fix the issue, and is causing another issue which is
also reported by @sdebacker so I am removing it.

The issue @quetzyg was having is hopefully fixed by #1228