recovered tests in genomix-data partially 

@jakebiesinger @JavierJia @anbangx @Elmira88 please have a check.
1. refactoring KmerFactoryTest is done while other types' tests is still on progress. If this KmerFactoryTest refactoring is reasonable, I can continue work on other tests.
2. removed EdgeMapTest, and cleaned duplicates tests in original KmerFactoryTest. 
3. Separate original KmerFactoryTest into two isolated test files called KmerFactoryFixedTest (corresponding to our original KmerFactoryTest which all use fixed test data as input), and KmerFactoryRandomTest(totally used random input data, increase the test random property and test pressure).
4. KmerFactoryRandomTest only need to set strMaxLength and strMinLength these 2 parameters in the setUp() function.After setting them, each test case will begin with a String "input" within the range(strMaxLength, strMinLength). Our testing input vkmer can be got by kmerFactory.getKmerByRead(kmerSize, input.getBytes(), 0) where kmerSize is determined by a range (1, input.length()) in a Random way.
5. Beside that, I added a class called RandomTestHelper which provide utility function for KmerFactoryRandomTest