docs+build: Prepare release of version 0.4.0

Change-Id: Ie5dfb3a1c7674cd426b89721c91ad59327517764
Refs: #3178
diff --git a/docs/release-notes/release-notes-0.3.1.rst b/docs/release-notes/release-notes-0.3.1.rst
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+ndn-cxx version 0.3.1
+---------------------
+
+Release date: March 3, 2015
+
+Changes since version 0.3.0:
+
+New features:
+^^^^^^^^^^^^^
+
+- **Management**
+
+  - Add isConnected() in :ndn-cxx:`signal::Connection` and :ndn-cxx:`signal::ScopedConnection`
+    (:issue:`2308`)
+
+  - Extend :ndn-cxx:`DummyClientFace` to process :ndn-cxx:`LocalControlHeader` (:issue:`2510`)
+
+  - Add CachingPolicy to :ndn-cxx:`LocalControlHeader` (:issue:`2183`)
+
+Updates and bug fixes:
+^^^^^^^^^^^^^^^^^^^^^^
+
+- **Wire encoding**
+
+  - Refactoring of :ndn-cxx:`EncodingImpl` class template (``EncodingBuffer`` and
+    ``EncodingEstimator``) (:issue:`2494`, :issue:`2490`)
+
+  - Change :ndn-cxx:`Block::fromBuffer` return type (:issue:`2553`)
+
+- **Miscellaneous tools**
+
+  - Mark ``Digest<Hash>::operator==`` as unsuitable in a security sensitive context
+    (:issue:`2395`)
+
+  - Restrict destruction of Signal from handler (:issue:`2313`)
+
+- **Documentation**
+
+  - Correct function names in security library tutorial (:issue:`2474`)
+
+  - Remind users to reinstall ports after OSX upgrade (:issue:`2284`)
+
+- **Tests**
+
+  - Fix global buffer overflow in ``ImplicitSha256Digest`` test case (:issue:`2307`)
+
+  - Change naming conventions for unit test files and test suite names (:issue:`2497`)
+
+- **Build**
+
+  - Explicitly define ``_GLIBCXX_USE_NANOSLEEP``, necessary for gcc < 4.8 in some environments
+    (:issue:`2499`)
+
+Removed:
+^^^^^^^^
+
+- Delete deprecated ``Block(std::istream&)`` constructor (:issue:`2241`)
+
+- Delete deprecated ``ndn::ptr_lib``, ``ndn::func_lib`` (:issue:`2110`)
+
+- Delete deprecated ``MetaInfo::TYPE_*`` (:issue:`2170`)