StringUtils.abbreviate handles empty abbrevMarker

[jordanjenkins]

StringUtils.abbreviate would not abbreviate properly when an empty String was passed to abbrevMarker or abbrevMarker is null Expected behaviour: abbreviate("much too long text", "", 13).equals("much too long") Actual behaviour: abbreviate("much too long text", "", 13).equals("much too long text")

Behaves the same when abbrevMarker is null.

Added if statements to handle empty and null abbrevMarker Passed all tests

[coveralls]

Coverage increased (+0.001%) to 95.377% when pulling 050682bcc76077c49338125c7a0357d3ab61f9d9 on jordanjenkins:StringUtilsAbbreviateFix into 8445d3a9911ec67f07b76c0c44cc4c8ac0c16178 on apache:master.