textareas with linefeeds - Fixes #1068
refactor textarea document manipulation into one place
Expose execute_script to SESSION_METHODS
Make sure multiple empty files are sent as nil, and not the empty string

Disproves #1108
Merge pull request #1104 from abotalov/expose_execute_script

Expose execute_script to SESSION_METHODS
test for within frame and scope resetting
reset scope when switching frames and windows - fixes Issue 1103
Merge pull request #1110 from twalpole/iframe

Push nil scope when switching windows and frames to fix issue 1103
support :wait option in `assert_selector` and `has_text?` matcher

closes #1105
Merge pull request #1111 from nashby/issue-1105

support :wait option in `assert_selector` and `has_text?` mather
Merge pull request #1069 from twalpole/textare_newline

Textarea with linefeeds - Fixes #1068