Update Huff.java

Changed the stringConvert method to return an int array of length 2, with the string's integer representation in the 0 index and the length of the string in the 1st index.

Changed the writeFile method to write the bit string integer with the proper number of bits, and to flush before closing the stream.
Merge pull request #5 from jdelo93/patch-5

Update Huff.java