chore: add .gitattributes
chore: add .gitattributes

so that git checkout on Windows uses LF and JSCS does not complain on
prerelease

BranchMetrics/cordova-ionic-phonegap-branch-deep-linking,BranchMetrics/Cordova-Ionic-PhoneGap-Deferred-Deep-Linking-SDK,BranchMetrics/cordova-ionic-phonegap-branch-deep-linking,BranchMetrics/Cordova-Ionic-PhoneGap-Deferred-Deep-Linking-SDK,BranchMetrics/cordova-ionic-phonegap-branch-deep-linking,BranchMetrics/cordova-ionic-phonegap-branch-deep-linking,BranchMetrics/Cordova-Ionic-PhoneGap-Deferred-Deep-Linking-SDK,BranchMetrics/Cordova-Ionic-PhoneGap-Deferred-Deep-Linking-SDK,BranchMetrics/cordova-ionic-phonegap-branch-deep-linking