Check the package id is set in the uninstall configure.

[hunkim]

It would be nice to give users a heads up in the configure rather than running 'perform' and giving them an error in the build.

Since we are already checking the existence of package id, and give an error:

Uninstall.java
// Check whether a value was provided
final String packageId = getPackageId();
if (Util.fixEmptyAndTrim(packageId) == null) {
AndroidEmulator.log(logger, Messages.PACKAGE_ID_NOT_SPECIFIED());
return false;
}

We can check that in the configure in advance.

This patch will bring a nice note in configure, and check the input.

[jenkinsadmin]

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[orrc]

Thanks!