Improvements to readme

[eximius313]

1. Karaf 4 section shows:

karafFeatures {
...

Shouldn't it be:

karaf {
    features {

?

2. features name should include version in documentation. Instead of:

karafFeatures {
  name = 'featuresName'
...

Readme should rather show:

karaf {
    features {
        name = "${project.name}-${version}"
...
}

3. Both features.name and features.outputFile could be also showed in the main example
4. Instead of using plenty od configurations and dependencies - why not use just two?

configurations {
  foo
  bar
}
dependencies {
  foo 'commons-io:commons-io:2.4'
  bar (
    'com.fasterxml.jackson.core:jackson-core:2.7.0',
    'com.fasterxml.jackson.core:jackson-databind:2.7.0'
  )
}

Moreover - using real names such as commons or json makes user think that they're some 'defaults' and not customizable by user