Update configure.ac

Added ubuntu 13.10 and libboost1.54-all-dev incompatibility instruction to the existing no boost_sleep warning.
Update build-unix.md

Added incompatibility and instruction regarding Ubuntu 13.10 and libboost1.54-all-dev
Make gitian builds consistent across platforms

Change Linux deps to use a zip archive rather than a gzipped tarball to
match win32
Rename Linux descriptor to gitian-linux.yml to match win32
Added automake to the macports depdency list as it was required to complete the autogen.sh step as it required aclocal (which isn't included in recent versions of xcode).
Merge pull request #3546

f4e72bf Make gitian builds consistent across platforms (Micha)
Merge pull request #3547

8d31e61 Added automake to the macports depdency list as it was required to complete the autogen.sh step as it required aclocal (which isn't included in recent versions of xcode). (Scott Willeke)
Merge pull request #3542

69843c8 Update build-unix.md (Christopher Latham)
720731d Update configure.ac (Christopher Latham)