http: use Address for bulk tx and utxo reads

[boymanjor]

The fixed endpoints are being considered for deprecation.
For now, this commit adds a warning message to the logs
and a TODO to deprecate once the necessary functionality
is added to the wallet API.

[codecov-io]

Codecov Report

Merging #93 into master will decrease coverage by 0.02%.
The diff coverage is 0%.

@@            Coverage Diff            @@
##           master     #93      +/-   ##
=========================================
- Coverage   55.23%   55.2%   -0.03%     
=========================================
  Files         109     109              
  Lines       27039   27047       +8     
  Branches     4472    4472              
=========================================
- Hits        14934   14932       -2     
- Misses      12105   12115      +10

Impacted Files	Coverage Δ
lib/node/http.js	38.36% <0%> (-0.78%)	⬇️
lib/coins/compress.js	55.06% <0%> (-1.27%)	⬇️

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[braydonf]

Ditto a comment at bcoin-org/bcoin#612 (comment)