some documentation and stylistic updates
Added required dependencies on opm-parser and CJSON
Removed explicit cJSON dependency from opm-core
Added CJSON_INCLUDE_DIRS to OPM_PARSER_INCLUDE_DIRS
Raised the opm-core boost dependency to 1.44 to reflect parser requirement
Provide dependency information for opm-benchmarks
Depend on Boost::iostreams

The benchmark library uses Boost::iostreams to do decompression. Since
we only scan for the Boost dependency once, this submodule is added to
all of the projects in order to have a coherent dependency on Boost.
Uniformly raise Boost version requirement to 1.44

Commit 70505ff raised opm-core's "Boost" requirement to version 1.44
in order to reflect the requirements of the opm-parser module.  This
commit propagates that requirement to all other known modules.
Set the boost version requirement to 1.44 - and added cJSON dependency
Reformat prerequisite file according to convention

This commit makes a few adjustments to the white-space of file
'opm-parser-prereqs.cmake' to honour the conventions of the other
*-prereqs.cmake files within the OPM project's module suites.

No functional changes.
Depend on Boost.Iostreams

The benchmark library uses Boost::iostreams to do decompression. Since
we only scan for the Boost dependency once, this submodule is added to
all of the projects in order to have a coherent dependency on Boost.
Fix mis-merge.

In propagating the requirements for opm-benchmarks to the other
modules I accidentally removed the 'opm-parser' prerequisite (see
commit 86439d6 for details).  This commit restores that prerequisite.
Restore C++-11 checks

While reformatting the parser-prereqs file I accidentally replaced
the feature search 'CXX11Features' with 'CXX10Features'.  This
commit fixes that blunder.
Defer searching for opm-parser

The "opm-parser" module is expected to become dependent upon the ERT
library.  Defer searching for the parser module until we've
established whether or not ERT is availble.

Suggested by: @andlaus
Elucidate description string for opm-parser.

The 'opm-parser' module is (currently) designed to parse ECL-type
simulation models.  Reflect that fact in its description.