Throwing a proper RuntimeException when a property could not be loaded f...

...or a client because it didn't have a property name after the namespace

The load method throws a ```java.lang.StringIndexOutOfBoundsException``` currently for properties like this -

myclient.ribbon.=baz
myclient.ribbon=bar

This PR throws a ```java.lang.RuntimeException``` with the name of the property which is invalid in the message of the exception instead of the ```java.lang.StringIndexOutOfBoundsException```

We could also just log an error and load rest of the properties but this would change the current behavior where the method returns after throwing the ```java.lang.StringIndexOutOfBoundsException``` which also happens to be a subclass of ```java.lang.RuntimeException```
@pstout Well what you suggested would not work straight away. Because for a property like ```myclient.ribbon=bar``` the namespace is ribbon and there is no property in there and that's why the code fails in the first place. We can just tell the user that there was some problem parsing properties in that namespace.