Release 1.5

This is a mini version that adds the _spiro_min_version_ parameter for spec files.

Commits:

b1e303f 2017-02-23 (HEAD -> master, tag: v1.5, origin/master, origin/HEAD) bump to 1.5 [Ben Meier]
119a914 2017-02-23 added examples and readme for min version stuff [Ben Meier]
c100f41 2017-02-23 added version number check in the spec file [Ben Meier]
e628eb8 2017-02-21 (tag: v1.4) bump version [Ben Meier]

Release Contents:

$ tar -tzf spiro-1.5.tgz | sort
./
./darwin_amd64/
./darwin_amd64/spiro
./linux_amd64/
./linux_amd64/spiro