Adds monero transaction feature flag & updates Travis CI to include feature flag enabled

[codecov[bot]]

Codecov Report

Merging #161 into v0.6.2 will decrease coverage by 4.12%. The diff coverage is 78.93%.

@@            Coverage Diff             @@
##           v0.6.2     #161      +/-   ##
==========================================
- Coverage   89.42%   85.29%   -4.13%     
==========================================
  Files         107      111       +4     
  Lines        7893     9284    +1391     
==========================================
+ Hits         7058     7919     +861     
- Misses        835     1365     +530     

Impacted Files	Coverage Δ
bitcoin/src/format.rs	71.42% <ø> (-7.52%)	:arrow_down:
bitcoin/src/network/mainnet.rs	85.18% <ø> (-3.71%)	:arrow_down:
bitcoin/src/network/testnet.rs	77.77% <ø> (-11.12%)	:arrow_down:
bitcoin/src/witness_program.rs	88.31% <0.00%> (-1.17%)	:arrow_down:
model/src/amount.rs	50.00% <ø> (ø)
model/src/public_key.rs	15.00% <ø> (ø)
model/src/transaction.rs	0.00% <0.00%> (ø)
monero/src/address.rs	91.13% <ø> (+0.11%)	:arrow_up:
zcash/src/address.rs	87.55% <0.00%> (-3.06%)	:arrow_down:
zcash/src/transaction.rs	53.15% <ø> (ø)
... and 59 more

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