La audit fixes

[sirnicolaz]

• close Issue A: Deposited Tokens Can Be Redeemed #90
• close Issue B: Unsettled Deposits Can Be Locked #91
• close Issue C: Missing Modifier Preventing the Update of Non-Existent Resolutions #92
• close Issue D: The Status of InternalMarket or ShareholderRegistry Can Be Set to Contributor Status #93
• close Suggestion 2: Add Check To Verify Token Transfer Return Value #95
• close Suggestion 3: Add Zero Address Checks #96
• close Suggestion 4: Remove Redundant Checks #97
• close Suggestion 5: Use an Updated and Non-Floating Pragma Version Consistently Across the Project #98
• close Deposit tokens mints extra NEOK to Governance Token contract  #119