Release v0.1.5

Changelog

dfe23f5 Add support for getting spendable balance
9146b47 Bump github.com/bitcoinschema/go-bitcoin from 0.3.13 to 0.3.15
1938abf Merge pull request #8 from tonicpow/dependabot/go_modules/master/github.com/bitcoinschema/go-bitcoin-0.3.15
5da562b Merge pull request #9 from galt-tr/spendableBalance
2db5174 Minor cleanup
312b1ae Removed old deps
d2651d5 Upgraded linter