updates
closes #58 ECGroup class handles bytes in hash call for python3
closes #59
closes #62 updates ecmodule
closes #63 updates
closes #65 fixes inconsistencies with ECGroup class
closes #64 implemented int() for ECGroup
cleaning ECGroup base module
closes #66 switched elliptic_curve mod to SHA-2
switching affected modules to SHA-2 as well
updates to fix Rabin
Merge branch 'dev' into 2.7-dev
tweaks to Rabin for 2.7