Merge pull request #395 from eed3si9n/wip/licenses

Add predefined list of licenses

core/src/main/scala/sbt/librarymanagement/License.scala

@@ -0,0 +1,24 @@
+package sbt.librarymanagement
+
+import java.net.URL
+
+/**
+ * Commonly used software licenses
+ * Names are SPDX ids:
+ * https://raw.githubusercontent.com/spdx/license-list-data/master/json/licenses.json
+ */
+object License {
+  lazy val Apache2: (String, URL) =
+    ("Apache-2.0", new URL("https://www.apache.org/licenses/LICENSE-2.0.txt"))
+
+  lazy val MIT: (String, URL) =
+    ("MIT", new URL("https://opensource.org/licenses/MIT"))
+
+  lazy val CC0: (String, URL) =
+    ("CC0-1.0", new URL("https://creativecommons.org/publicdomain/zero/1.0/legalcode"))
+
+  def PublicDomain: (String, URL) = CC0
+
+  lazy val GPL3_or_later: (String, URL) =
+    ("GPL-3.0-or-later", new URL("https://spdx.org/licenses/GPL-3.0-or-later.html"))
+}