Replace Butterknife with Kotlin Android Extensions

[juanignaciomolina]

# Replace Butterknife with Kotlin Android Extensions

Replace the view binding library, from Butterknife to KotlinAndroidExtensions:
https://kotlinlang.org/docs/tutorials/android-plugin.html

Also, I recommend using the prefix v for variables that access views from the XML.
Examples:
vButton
vMainLayout
vRecyclerView