Merge pull request #3 from sfitts/master

Fix for running tests on Windows
Updated gradle wrapper to version 1.11
Renamed method DockerTask.instruction to addInstruction
Support for VOLUME dockerfile command
Support for ENV dockerfile command
Switching to official dockerfile/java image as default and java7 image
Fixed typo
Updating license headers (year)
Added changelog, updated docs to version 1.1
Fixed automatic versioning based on git describe
Added instruction to set tag version (default :latest)
Handling error of docker process execution.
Merge pull request #7 from Teudimundo/handling_command_failure

Handling error of docker process execution.
Added possibility to build without group property (Issue #8).
Updated docs and example to version 1.1.1.
added Java8 as option for base image
updated to use the proper docker image -- java8-pier
Merge pull request #9 from aglover/java8

added Java8 as option for base image
Added download link to bintray.
Added badge to Drone CI