add logcat support for appium android
we use the selenium facility for getting log types and log entries.
in this case, simply ask for logs of type 'logcat' and you'll get them
Merge pull request #996 from jlipps/master

Retrieve logcat logs for android
refactor session proxy code
allow capturing logcat for selendroid
Save iOS screenshots to /tmp/appium-ios-screenshots/

Fix #983

Fix instruments dir
Merge pull request #998 from jlipps/master

allow logcat capture for selendroid too
fix failing mobile safari test
try out a fix for (null).tap issues
hat tip to @kinghenry3
changelog and bump to 0.8.4 for npm publish
Merge pull request #997 from bootstraponline/fix_ios_screenshot

Save iOS screenshots to /tmp/appium-ios-screenshots/
Change to make Android requests more generic and allow install, uninstall and isInstalled to be called without having serial id defined.
Merge pull request #1000 from snevesbarros/abd_fix

Change to allow isInstalled, install, uninstall to be called for Android without providing serial id