Strip null's from end of strings

[grantseltzer]

Currently when tracing strings a lot of padded null's are appended to the end of strings:

[*] sudo ./bin/oster --function-to-trace='main.test_function(int, string)' ./bin/test-prog
{"Type":"INT","Value":"3"}
{"Type":"STRING","Value":"hello\u0000\u0000\u0000\u0000\u0000\u0000\u0000"}

Let's remove those after treating the user space byte array as little endian.

[grantseltzer]

They were actually unicode 0's but this is complete