Migrate ISSM to GitHub repo (#172)

ISSM:
- Change to git address. Added url_for_version function
- Add url_for_version function
- Add release version

packages/issm/package.py

@@ -12,9 +12,10 @@ class Issm(AutotoolsPackage):
     """Ice-sheet and Sea-Level System Model"""
 
     homepage = "https://issm.jpl.nasa.gov/"
-    svn = "https://issm.ess.uci.edu/svn/issm/issm/trunk"
+    git = "https://github.com/ISSMteam/ISSM.git"
 
     version("develop")
+    version("4.24", sha256="0487bd025f37be4a39dfd48b047de6a6423e310dfe5281dbd9a52aa35b26151a")
 
     depends_on("autoconf", type="build")
     depends_on("automake", type="build")
@@ -25,6 +26,9 @@ class Issm(AutotoolsPackage):
     depends_on("petsc+metis+mumps+scalapack")
     depends_on("m1qn3")
 
+    def url_for_version(self, version):
+        return "https://github.com/ISSMteam/ISSM/tarball/v{0}".format(version)
+
     def autoreconf(self, spec, prefix):
         autoreconf("--install", "--verbose", "--force")