Configurable lookup of version to bump

[lukaszwawrzyk]

By default we are looking for versions to replace in all WORKSPACE, BUILD, .bzl and .bazel files. Users should be able to configure acceptable paths in the form of globs or regexes, with an option to exclude. The configuration could be global, but also scoped to a specific version system (like look for jvm_rules_external dependencies in this file, but for scala version in that file, and for bazel rules version in different file).