Hotfix travis release condition

[mcspr]

Travis pulls tag as branch, so branch === tag.
Use same regexp as earlier build.sh did, matching ^ MAJOR dot MINOR dot PATCH $

Sorry, only noticed it yesterday tweaking nightlies conditions with this at the top for tagged builds:

git clone --depth=50 --branch=20180708 https://github.com/mcspr/espurna-travis-test.git mcspr/espurna-travis-test

[mcspr]

...and I did trigger api build of the dev / c16b380 because master release did not trigger (my bad, #1007 broke this)
https://github.com/mcspr/espurna-travis-test/releases/tag/20180710

curl -s https://api.github.com/repos/mcspr/espurna-travis-test/releases/tags/20180710 | grep browser_download_url | cut -d ':' -f2- lists links (they are not direct, require -L) to all of the release assets