Release v0.3.8

Changelog

dd4213f Added another test case
67e9de7 Added more test cases for CreateTxWithChange
ea1034d Added more timeout, added exclusion
c783d2a Minor link updates
313427b Removed comment (not needed)
bafe69c Removed old constants, added warnings
08c8bc9 Updated makefiles
132a566 Upgraded crypto dep
78cb7d3 Upgraded deps, run on both versions of Go
889edd3 Using new go-bt Fee now