Documentation for consuming published wheels

[devinrsmith]

With the introduction of the published wheels, it becomes necessary to ensure libjvm is "preloaded" appropriately.

It should probably suggest something like:

import jpyutil
# This needs to happen before `import jpy`
jpyutil.preload_jvm_dll()

import jpy

and/or

import jpyutil
# This needs to happen before `import jpy`
jpyutil.init_jvm()

import jpy

but it may need to be more nuanced to account for different situations.

[devinrsmith]

Spawned from #80

[mkanoor]

On MAC it needs JAVA_HOME to be set especially if you have multiple versions of Java installed