add checksum support for extensions
enhance exts_list unit test for checking extension checksums
Merge pull request #807 from boegel/extension_checksums

add checksum support for extensions
define two types of default operator, exit with error on (toolchain) version operator parsing failure
clean up imports
fix parsing w.r.t. key-value entries in sections (just pass them down), start implementation of get_specs_for function
further flesh out get_config_dict to something that works, add False/True to allowed builtins used in Python header
pass down version/toolchain specifications to parsing function, implement asdict function to obtain dict representation of EasyConfig instance
add unit test for checking equivalency of easyconfigs files in old and new format
make sure versions are provided as strings in easyconfig dict, fix unit tests
pass down software build specs from command line easyconfig parser
add unit test for toy build using format 2.0 easyconfig file, reorganize toy build unit test module
make sure that requested version and toolchain are supported by easyconfig, fix example gzip.eb easyconfig
fix easyconfigversion unit tests w.r.t. parsing failures
fix easyconfig parser unit test, default version is first listed version
use template constants in tested easyconfigs
enforce operator in toolchain version strings, ' == ' should be used instead of ' '
fix toolchains spec in other format 2.0 test easyconfigs
rework class parameter for EasyBlock/EasyConfig to build_options and build_specs
adjust to changed EasyBlock/EasyBuild class parameters