2.8

Changes to the library:

• add support for setting atime, ctime, mtime and birthtime (#50 and #63)
• tell libarchive when writing an archive is aborted due to an exception (#53)
• add support for getting uid and gid (#57)
• add support for high resolution timestamps (#58)
• add two new archive readers: stream_reader and custom_reader (#60)
• add missing archive extraction flags (#61)
• add the lz4 and warc formats (#62)
• add support for write options and uid/gid lookup (#72)

Tests:

• drop python 3.3 and add 3.6
• add segfault detection (#59)
• test against libarchive 3.3.2 instead of 3.1.2 (#70)