Add failing bounds checks for views

See #25
Bounds check the `len` of a Cstruct in the BE/LE modules.

Closes #25
Document that the `Cstruct.LE/BE` functions can raise `Invalid_argument`

Noted missing by @dbuenzli
Sync CHANGES and bump to 1.3.0 working version
Fix a vitypo
Add Lwt_cstruct.complete convenience function

When dealing with functions like 'read' and 'write' which return
an integer which means:
  0: End_of_file
  n: n bytes written
we can now write 'complete read' which will keep executing 'read'
until the whole buffer has been processed, returning () or
failing with End_of_file.

Signed-off-by: David Scott <dave.scott@citrix.com>
fix docstrings to use `@raise` and fix exception names

Suggested by @dbuenzli
Merge pull request #26 from avsm/more-bounds-on-views

More bounds on views
Merge branch 'complete' of git://github.com/djs55/ocaml-cstruct into djs55-complete

Conflicts:
	CHANGES
Add `Sexplib` conversion functions to `Cstruct.t` buffers

Closes #27 #22
add opam file for more convenient pinning
update travis depends
Merge pull request #29 from avsm/add-sexp

Add `Sexplib` conversion functions to `Cstruct.t` buffers
Fix build status url
view bounds on 1-byte get/set
test 1-byte bounds
Bump to 1.3.1
add negative bounds checks to accessors
more aggresive tests of getter bounds checking
more aggresive tests of setter bounds checking