Tests for JSON Pointers

[erosb]

Tests for this PR: stleary/JSON-java#222

[stleary]

Sorry, will be some delay, having problems getting coverage to work in my dev environment.

[stleary]

Thank goodness for dev environments on multiple boxes. Coverage is fine, thanks for taking the time to do these tests. You may, if you want, add testing for JSONObject.query() and JSONArray.query(), otherwise I can add them. JunitTestSuite.java should have JSONPointer.class added to the SuiteClasses annotation. Otherwise all looks OK so far.

[johnjaylward]

Maybe just add a test for this:

Builder b = JSONPointer.builder().append("key1");
JSONPointer jp1 = b.build();
b.append("key2");
JSONPointer jp2 = b.build();
if(jp1.toString().equals(jp2.toString()){
    throw new Exception("Oops, my pointers are sharing a backing array");
}