rewritten dict creation in order to maintain python 2.6 compatibility

Python 2.6 has not implemented comprehensive dict creation yet (cf. Pep
274). In order to run skrf in python 2.6 all compehensive dict creations
have been rewritten with dict creation of comprehensive lists.
Merge branch 'develop' of github.com:hohe/scikit-rf into develop
Merge pull request #12 from hohe/develop

Maintain Python 2.6 compability