added `launchCommand` option

### `--launchCommand="your_command_here %U"`

Specify a custom command to launch. `%U` will be replaced with the URL
 that corresponds with the working git directory.

NOTE: This will execute *before* opening the browser window if
 the `launchBrowser` option is `true`.

### Example:

```shell
# Override the browser launch command; use chrome's "--app"
#   argument to get a new, chromeless window for that "native feel"
ungit --launchBrowser=0 --launchCommand="chrome --app=%U"
```
better explanation in config.js
fixed case where neither launchCommand/Browser specified
Merge pull request #273 from namuol/master

Added custom launch command option.
Don't serialize the password as the user. Fixes #275
Don't append unnecessary "" to git status. Fixes #267

Seems like this may cause git to not see changes in symlinked directories
Don't erase title when toggling amend. Fixes #286

Change-Id: I74925622176d265d73ecfea44a3251603b446b29
Allow checking out nodes. Fixes #285

Change-Id: I34770623039a392ab96f8ca37bc41f2e6f3745ba
Adding a button to create dir when path doesn't exist. #282
Change create dir to post and fixing current test cases
Adding clicktest
Adding valid path check
Adding multi layer mkdir
Adding/using multi layer mkdir in testing
Fix image in README

Fix the screenshot in the README so that it works on the GitHub repo's home page.
Merge pull request #288 from Ajedi32/patch-1

Fix image in README
Add some consideration bullet points to CONTRIBUTING.md
Update to bootstrap 3.0.3

Change-Id: I95d2fafec01fce5fd3550a6762743c64741a3cb2
Use button group for staging file actions

Change-Id: I3fe0338780453cc1d0e5da2637271203b1d07c52
Fix wide container class

Change-Id: I5c4671996c11a158e6cfed2449778b1136ae27a9