Merge pull request #98 from zlsun/master

Change cwd to %USERPROFILE% before executing command.
Add Empty Check for GetEnvironmentVariable Method.
Add folder existence check for USERPROFILE environment variable.
#21 Add Disable option for each plugin.
add search for Firefox bookmarks
Make sure the places.sqlite file exists

before loading Firefox bookmarks.
update plugin.json for the BrowserBookmarks plugin
Update README.md
Merge pull request #99 from JohnTheGr8/master

Firefox bookmarks
cache Firefox bookmarks and support pinyin search
improved Firefox bookmark-parsing query

now gets bookmark title from moz_bookmarks table instead of moz_places
Merge pull request #100 from JohnTheGr8/master

Improvements for Firefox bookmarks
close #21 Allow user to set their custom ActionKeyword
Merge branch 'master' of https://github.com/qianlifeng/Wox.git
Some plugin style changes.
Move CMD settings to CMD plugin details.
Add Executable Plugin Loader
Refactoring Plugin Loader [WIP].
Update README.md
Update README.md