Update guava dependency

[jimkont]

The guava dependency in this project is too old and creates conflicts in projects that use a newer version. The error I currently get is
Exception in thread "main" java.lang.NoSuchMethodError: com.google.common.base.Preconditions.checkArgument(ZLjava/lang/String;Ljava/lang/Object;)V

If you google this, this issue happened in other projects like

• PageFactory.initElements throwing java.lang.NoSuchMethodError: com.google.common.base.Preconditions.checkArgument(ZLjava/lang/String;J)V appium/java-client#588
• Exception in thread "main" java.lang.NoSuchMethodError: com.google.common.base.Joiner$MapJoiner.appendTo SeleniumHQ/selenium-google-code-issue-archive#7940
• Unable to launch chrome browser using selenium 3.1.0 SeleniumHQ/selenium#3540
• Preconditions.checkState throws NoSuchMethodError google/guava#2380

Propose to update the quava version from version 18 to version 21

[Hronom]

I'm suggesting to upgrade up to 22