Assume that people use bundler

It's ubiquitous now.
Improve save_page for binary content
Issue #1229 - reset touched after session is reset
Merge pull request #1230 from lesliepc16/reset_touched

Issue #1229 - reset touched after session is reset
add refute_selector as alias of assert_no_selector
Merge pull request #1234 from gregmolnar/refute

add refute_selector as alias of assert_no_selector
Merge pull request #1233 from abotalov/add_ruby_version_to_gitignore

Add .ruby-version and .ruby-gemset to .gitignore
Merge pull request #1222 from joliss/readme

Assume that people use bundler
Merge pull request #1223 from cschramm/patch-1

Improve save_page for binary content