fix tee and egrep paths
android: fix local.properties file (sdk.dir)

the local.properties file contains the system's path to the android-sdk;
as this path differs for each platform the local.properties file has to
be replaced or removed

from now on the local.properties will be removed if the environment
variable ANDROID_HOME exists; if not, cordova-build tries to find the
android executable via 'whereis' and overwrites the local.properties
add iosskipsign argument for dev purposes