Add Installation and Upgrade Messages

- Add 'messages.json', 'messages' folder and '0.3.0.md' as required
  by Package Control

Author: stephenfin

messages.json

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+{
+    "install": "README.rst",
+    "0.3.0": "messages/0.3.0.md"
+}

messages/0.3.0.md

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+Changes in 0.3.0
+================
+
+- Added support for Sublime Text 3
+  * Rename ``jump_back`` commmand to ``jump_prev`` to prevent conflict in ST3
+  * Remove ``jump_back_to_last_modification`` command
+  * Numerous fixes to ensure Python compatibility
+  * Add abstraction library for ``sublime.view`` edit functions (``begin_edit``
+    and ``end_edit``) for which the API differs between ST2 and ST3
+  * Add calls to ``sublime.error_message`` when errors occur
+  * Apply general changes needed by Python3, i.e. print as a function
+- Major refactoring of code base
+  * Logically reorder number of functions
+  * Add unit tests for number of functions
+  * Update and move existing unit tests to separate files
+  * Add documentation to majority of functions
+  * Add documentation to settings files
+  * Remove unused functions (dead code)
+  * Remove large swathes of text and place in separate files
+  * Move small, one-time functions into inner functions or merge into other
+    other functions
+  * General formatting to abide to PEP-8 coding standards
+- Updated README and other documentation
+  * Port to reStructuredText
+  * Add additional sections for different package managers
+  * Minor rewrites and spelling corrections
+  * General formatting
+- Additional Changes
+  * Remove ``ctags`` executable files
+
+Fixes
+=====
+
+* Broken "Jump Back To Last Modification" command?, #159
+* To support customizable filename of tags file, #157
+* Corrected wrong documentation, added correct instructions for OS X 10.8, #151
+* Error in readme.md, #150
+* CTags can't jump_back in ST3, #148
+* Can't build CTags in OSX Mountain Lion, #146
+* Why does Navigate to Definition (and Jump Back) select text?, #128
+* Jump Back should go back to the line you were on, #127
+* Silently fails if ctags isn't installed, #93
+
+And the big one:
+
+* Incompatibility with ST3 beta, #115
+
+Resolves
+========
+
+N/A
+
+*******************************************************************************
+
+For more detailed information about these changes, run ``git v0.2.0..v0.3.0``
+on the Git repository found [here](https://github.com/SublimeText/CTags).