disable run-all rspec on guard launch

There is a Guard bug here I think.
more concise error checking for .dylib_path_from_options

Should probably remove that test. (>_>)
rake spec should run device tests

The device tests will only run if there are connected devices.
NB - iOS8 devices are skipped.
sim_control can detect Xcode >= 6.0 sim_udids
don't enable accessibility when targeting device

WIP - Still need to handle Xcode >= 6.0 'named simulators'
ruby interface to the 'simctl list' command
sim control needs check for xcode >= 5.1
support for cons'ing a list of Xcode 6 simulators
support for detecting Xcode 6 named simulators
marks SimControl #simulator NYI for Xcode 5.1.1
disabled flickering sim quit/launch on Travis CI

Pass > 75% of the time and this behavior is tested repeated in other
specs.
remove redundant info from DEBUG log
disable dylib injection tests on Travis CI

90% passing, but the feature is too unstable for Travis.
Merge pull request #16 from calabash/feature/detecting-simulator-in-run-options

only enable accessibility when targeting a simulator