Update to OASIS 0.4.5

Signed-off-by: John Else <john.else@citrix.com>
Remove explicit addition of -bin-annot flag

Oasis seems to pass this by default now.

Signed-off-by: John Else <john.else@citrix.com>
ppa uses OCaml 4.02.1, not 4.02.0

Signed-off-by: John Else <john.else@citrix.com>
travis: update OPAM dependency installation

Signed-off-by: John Else <john.else@citrix.com>
Merge pull request #17 from johnelse/build-tidying

Build tidying