Rake tasks runner support for TeamCity 4.x and newer

=============
1. Build
 * Checkout ruby sources from https://github.com/JetBrains/intellij-plugins/tree/master/ruby-testing/src/rb/testing into "lib/rb" directory
 * Open project in IntelliJ IDEA (https://jetbrains.com/idea)
 * In IntelliJ IDEA configure TeamCityDistribution Path Variable. It should point to directory containing TeamCity.
      You may download and unpack TeamCity-XXXXX.tar.gz (https://jetbrains.com/teamcity) into some folder.
      You may read more about Path Variables in IntelliJ IDEA help.
 * Build -> Build Artifacts... -> plugin_zip

2. Deploying
 * Copy "out/artifacts/plugin_zip/rake-runner.zip" to "[TeamCityDataDirectory]/plugins" folder

3. Sources

 |- root
 |--- [rake-runner-agent] - Agent's part of TeamCity Rake Runner, JAVA sources
 |--- [rake-runner-common] - Common code for Agent's and Server's parts or TeamCity Rake Runner, JAVA
 |--- [rake-runner-server] - Server's part of TeamCity Rake Runner, JAVA
 |--- [rake-runner-test] - Tests for rake-runner. TeamCity tests API is required for running tests
 |--- [lib/rb] - Unpacked RUBY part of plugin.
 |--- [out] - Compilation output directory
 |--- [out/artifacts] - Build artifacts
 |--- copyright.txt - Copyright for sources
 |--- HowToBuild.txt - this file

4. Internal Properties

  Debug loggers options:
  System properties:
   * "teamcity.rake.runner.debug.mode" - set variable to enable loggin from JAVA code of agent part