Streamline release process

[jvkersch]

vpsearch is a small package and (deliberately) plays fast and loose with the release process (the release process consists just of bumping the version number and tagging the appropriate commit on master). As the package becomes more widely used, it may make sense to adopt one of the versioning/release schemes from other Enthought open source projects.

[jvkersch]

Note: having a more streamlined release process will also make it easier to automate certain release-related tasks, such as building and uploading wheels.