TYRUS-274 bug fix

Hi Pavel,

Like we discussed, I made the change to core/src/main/java/org/glassfish/tyrus/core/InputStreamBuffer.java and created a new test /e2e/standard-config/src/test/java/org/glassfish/tyrus/test/standard_config/BufferedInputStreamTest.java.

Please try to take the changes into 1.5 release.

Let me know at raghuramcbz at (gmail.com), 
Thanks!
--
Raghu