Move PrettyPatch related code to prettypatch.py
https://bugs.webkit.org/show_bug.cgi?id=124937

Patch by Dániel Bátyai <Batyai.Daniel@stud.u-szeged.hu> on 2013-12-07
Reviewed by Ryosuke Niwa.

This code seems to have a better place here than in Port, since PrettyPatch already knows
pretty_patch_path, and this also unifies the usage of PrettyPatch

* Scripts/webkitpy/common/prettypatch.py:
(PrettyPatch.__init__):
(PrettyPatch.pretty_diff):
(PrettyPatch):
(PrettyPatch.pretty_patch_available):
(PrettyPatch.check_pretty_patch):
(PrettyPatch.pretty_patch_text):
* Scripts/webkitpy/layout_tests/controllers/test_result_writer.py:
(TestResultWriter.create_text_diff_and_write_result):
* Scripts/webkitpy/layout_tests/models/test_run_results.py:
(summarize_results):
* Scripts/webkitpy/port/base.py:
(Port.__init__):
(Port.wdiff_available):
(Port.check_image_diff):
(Port.wdiff_text):
* Scripts/webkitpy/port/base_unittest.py:
(PortTest.test_pretty_patch_os_error):
(PortTest.test_pretty_patch_script_error):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@160271 268f45cc-cd09-0410-ab3c-d52691b4dbfc