Gitiles: Implement Buck driven build

Until extension system is released by Buck team [1], factor out
existing Buck building blocks as Bucklets in standalone git
repository and reuse it as Git submodule to implement Buck driven
build [2].

To build gitiles `gitiles` target is used:

  buck build gitiles

To build servlet, sources and javadoc in addition, `all` target is used:

  buck build all

that produces:

  buck-out/gen/gitiles.war
  buck-out/gen/servlet.jar
  buck-out/gen/src.jar
  buck-out/gen/javadoc.jar

To execute the tests:

  buck test --all

To generate eclipse project:

  bucklets/tools/eclipse.py

To fetch sources for all dependent libraries too:

  bucklets/tools/eclipse.py --src

To install gitiles-servlet into local Maven repository:

  buck build mvn_install

To deploy gitiles-servlet into remote Maven repository:

  buck build mvn_deploy

[1] http://stackoverflow.com/questions/16681527/buck-vs-gradle-pros-and-cons-for-android-build-systems
[2] https://gerrit.googlesource.com/bucklets

Change-Id: Ib824dac6423d69c298f9c30ed7a0c05b4d6447c0

.buckconfig

diff --git a/.buckconfig b/.buckconfig
new file mode 100644
index 0000000..78b3922
--- /dev/null
+++ b/.buckconfig
@@ -0,0 +1,15 @@
+[alias]
+  gitiles = //:gitiles
+  all = //:all
+  in = //:install
+  mvn_install = //:install
+  mvn_deploy = //:deploy
+
+[buildfile]
+  includes = //bucklets/java7.bucklet
+
+[java]
+  src_roots = java, resources
+
+[project]
+  ignore = .git