Configuration: Use 'app' capability instead of 'applicationPath'

[knysh]

'app' capability fully cover what we have done in applicationPath, so need to mark all related methods as deprecated

[mialeska]

implemented in dotnet: aquality-automation/aquality-appium-mobile-dotnet#25

[mialeska]

we still might need access to getApplicationPath() methods for some reason, so better just to use applicationPath for this purposes, same as was implemented in dotnet