LP-83 first set of changes for make Pausable. Adding openzepplin pausable.

[codecov-io]

Codecov Report

Merging #43 into master will not change coverage. The diff coverage is 100%.

@@           Coverage Diff           @@
##           master      #43   +/-   ##
=======================================
  Coverage   96.52%   96.52%           
=======================================
  Files           4        4           
  Lines         115      115           
  Branches       25       25           
=======================================
  Hits          111      111           
  Misses          4        4

Impacted Files	Coverage Δ
contracts/LinniaRecords.sol	98.27% <100%> (ø)	:arrow_up:
contracts/LinniaUsers.sol	94.73% <100%> (ø)	:arrow_up:
contracts/LinniaPermissions.sol	95.23% <100%> (ø)	:arrow_up:

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[libertylocked]

Hub functions are only callable by owner, so there's no need to pause them. Maybe add pausable to other contracts, like users (register), records (upload, attest, etc), permissions (share)

I'm not sure if it's necessary to replace expect throw with assert revert. It may be a nice to have thing. Maybe in another PR?

[godfreyhobbs]

Will update other contracts in follow-up PR.

[godfreyhobbs]

I am going to merge this blocked PR in the morning, as I feel that I have addressed all requested changes and this is a pretty simple PR and it is now blocking other work.

The abi.encodePacked is actually part of the already approved PR #29 to 0.4.24. It only ended up here as the other PR took 11 days to get approval

[libertylocked]

29 wasn't a priority and I did not approve it.

Unfortunately I did not see that you are packing a single argument. The correct way is to covert it to bytes