Travis: fix the installability detection.
leveldb: add missing omake dep and libsnappy deps
Travis: fix install detection.

The previous fix in 301d8f1a9d6d024faf1834585a01bdfea20efa91 didn't
take into account that allpkgs is space separated and not on multiple
lines, so grepping the start of a word wont work.
Merge pull request #1552 from mirage/master

Fix Travis
Merge branch 'master' into mfp-master
Merge branch 'deriving-yojson' of git://github.com/hhugo/opam-repository into hhugo-deriving-yojson
Merge branch 'openflow.0.2.0' of git://github.com/seliopou/opam-repository into combined-fixed-with-fixed-travis
Merge branch 'aliases' of git://github.com/hhugo/opam-repository into combined-fixed-with-fixed-travis
Merge branch 'acpc_1.0' of git://github.com/UnixJunkie/opam-repository into combined-fixed-with-fixed-travis
leveldb.1.0.2: link explicitly against libstdc++ (and -lm for good measure).
acpc: fix typo that broke installation
packet: restrict to ocaml 4+ (due to use of `List.iteri`)
Merge pull request #1559 from mirage/combined-fixed-with-fixed-travis

Combined pull request with fixed Travis
leveldb.1.0.2: also link against libsnappy.
Merge branch 'master' of git://github.com/iguer/opam-repository into more-combined-fixes
Merge branch 'why3.0.82' of git://github.com/bobot/opam-repository into more-combined-fixes
Merge branch 'master' of git://github.com/jpdeplaix/opam-repository into more-combined-fixes
Merge branch 'aws' of git://github.com/hhugo/opam-repository into more-combined-fixes
obigstore.0.9.1: disable parallel build so as to get more clear CI logs.
Merge pull request #1560 from mirage/more-combined-fixes

More combined fixes
Merge branch 'camlzip' of git://github.com/hhugo/opam-repository into final-changes