Merge branch 'mrtazz-release-0-5-2'

release v0.5.1

release v0.5.0

bump to 0.4.4

only release packages from gcc builds

release v0.4.2

bump to 0.4.1

update CHANGELOG and bump to v0.4.0

this closes mrtazz#38

update CHANGELOG for 0.3.0 and bump version

v0.2.0 (19th April 2015)

- support basic auth
- Add header's to response object
- fix memory leaks related to curl cleanup
- add autotools build
- add CONTRIBUTING.md
- add vendorized gtest