Add changelog

CHANGELOG.md

+# Changelog
+
+## Version 1.0
+
+*July 2, 2014* [view issues](https://github.com/tripit/slate/issues?milestone=1&state=closed)
+
+**Features:**
+
+- Responsive designs for phones and tablets
+- Started tagging versions
+
+**Fixes:**
+
+- Fixed 'unrecognized expression' error
+- Fixed #undefined hash bug
+- Fixed bug where the current language tab would be unselected
+- Fixed bug where tocify wouldn't highlight the current section while searching
+- Fixed bug where ids of header tags would have special characters that caused problems
+- Updated layout so that pages with disabled search wouldn't load search.js
+- Cleaned up Javascript
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