Updated SnakeYaml version to work on Android devices

[itsymbal]

The current version of Yaml (1.14) doesn't work on Android devices or emulators. The newer version supports Android.
Unfortunately, it uses the SNAPSHOT version of the library... SAD! - which means I won't be able to use it offline on the subway... but at least it works.
If there's a better way to do it, by all means, use that way.
The current 1.14 version causes this exception:

java.lang.NoClassDefFoundError: Failed resolution of: Ljava/beans/Introspector;
at org.yaml.snakeyaml.introspector.PropertyUtils.getPropertiesMap(PropertyUtils.java:63)

I'm going to try to figure out a way to share yaml and json between test and androidTest and update the README.

[koral--]

We are using stock mockwebserverplus but with swapped snakeyaml dependency in our Android projects. build.gradle looks like that:

	androidTestCompile('com.orhanobut:mockwebserverplus:1.0.0') {
		exclude module: 'snakeyaml'
	}
	androidTestCompile 'pl.droidsonroids.yaml:snakeyaml:1.18-android'

That artifact is published to maven central, so no additional repository is needed.
'pl.droidsonroids.yaml:snakeyaml is based on this source: https://github.com/bmoliveira/snake-yaml

[itsymbal]

That's even better. @orhanobut Should I update the dependency in this PR to use the one @koral suggested? That seems like a better option than relying on a SNAPSHOT