Update deposit contract according to v0.6.1#130

Merged

mkalinin merged 16 commits intodevelopfrom

spec/deposit-contract

May 21, 2019

Commits on May 9, 2019

Merge branch 'develop' into spec/deposit-contract
zilm13
committed

Commits on May 15, 2019

pow: deposit contract clean up
zilm13
committed

Commits on May 16, 2019

Commits on May 17, 2019

Commits on May 20, 2019

pow: Merkle Tree interface method renamed to be abstract and clean
zilm13
committed

Commits on May 21, 2019