Fix #71 Support annotated tags in LogOp

Objects in include/exclude on LogOp are still resolved to rev strings.
The revstrings are resolved to peeled RevObjects to get the ObjectId of
the underlying commit. The peeling gets past the issues with annotated
tags.

src/main/groovy/org/ajoberstar/grgit/operation/LogOp.groovy

@@ -91,7 +91,7 @@ class LogOp implements Callable<List<Commit>> {
 		ResolveService resolve = new ResolveService(repo)
 		def toObjectId = { rev ->
 			String revstr = resolve.toRevisionString(rev)
-			JGitUtil.resolveObject(repo, revstr)
+			JGitUtil.resolveRevObject(repo, revstr, true).getId()
 		}
 
 		includes.collect(toObjectId).each { object ->

src/main/groovy/org/ajoberstar/grgit/util/JGitUtil.groovy

@@ -78,14 +78,16 @@ class JGitUtil {
 	 * Resolves a JGit {@code RevObject} using the given revision string.
 	 * @param repo the Grgit repository to resolve the object from
 	 * @param revstr the revision string to use
+	 * @param peel whether or not to peel the resolved object
 	 * @return the resolved object
 	 * @throws GrgitException if the object cannot be resolved
 	 */
-	static RevObject resolveRevObject(Repository repo, String revstr) {
+	static RevObject resolveRevObject(Repository repo, String revstr, boolean peel = false) {
 		ObjectId id = resolveObject(repo, revstr)
 		RevWalk walk = new RevWalk(repo.jgit.repository)
 		try {
-			return walk.parseAny(id)
+			RevObject rev = walk.parseAny(id)
+			return peel ? walk.peel(rev) : rev
 		} catch (MissingObjectException e) {
 			throw new GrgitException("Supplied object does not exist: ${revstr}", e)
 		} catch (IOException e) {

src/test/groovy/org/ajoberstar/grgit/operation/LogOpSpec.groovy

@@ -39,6 +39,7 @@ class LogOpSpec extends SimpleGitOpSpec {
 		testFile1 << '2'
 		grgit.add(patterns: ['.'])
 		commits << grgit.commit(message: 'second commit')
+		grgit.tag.add(name: 'v1.0.0', message: 'annotated tag')
 
 		grgit.checkout(branch: intToCommit(0).id)
 		testFile1 << '3'
@@ -85,4 +86,9 @@ class LogOpSpec extends SimpleGitOpSpec {
 		expect:
 		grgit.log(paths:['2.txt']) == [5, 0].collect(intToCommit)
 	}
+
+	def 'log with annotated tag short name works'() {
+		expect:
+		grgit.log(includes: ['v1.0.0']) == [1, 0].collect(intToCommit)
+	}
 }