Add function to append n bytes
Make test a little nicer
Add const to append parameters
fix compilation on linux

include `sys/types.h` for the `ssize_t` def.

closes #5.
fix header guard
Release 0.2.1
travis: setup
test: Fix memory leaks
travis: Fail the build if any memory is leaked
Remove spurious print
Free the buffer
Merge pull request #8 from marcomorain/append-n

Add function to append n bytes
Release 0.3.0