Material Design, UI and UX improvements and quite a lot of bugfixes

This is probably the largest Pull Request here yet, I should have split it up into multiple seperate ones, but it was easier to do this way.

[**Screenhots**](http://imgur.com/a/bYHz6 "QuasselDroid Redesign")
[**APKs**](https://github.com/justjanne/QuasselDroid/releases)

Here’s a summary of the changes this Pull Request does:

UI:
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- Replaced ActionBarSherlock with the new AppCompat implementation
- Added DetailFragment as a right navigation drawer for QueryBuffers
- Changed the whole UI to use Material Design.
- Updated Notifications
- Replaced most icons with new ones from https://github.com/joppuyo and Android Lollipop default icons
- Rewrote sender color system

Misc:
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- Made a lot of stuff more modular, allowing for easier modification
- Moved **ALL** strings out of the code into the strings.xml, also sorted that file properly to make translations easier
- Pushed the minimum API level to 14 (Android 4.0)
- Added support for automated Travis building and testing

Bugfixes:
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- Fixed Notifications: #180 and #26, ~~hopefully~~ confirmed #195 
- Fixed NickCompletion: #57
- Fixed #42 (partially) by saving the last state in the app, this stores the state beyond reconnect, but the state is lost at reboot of the phone
- Fixed UI bugs #76, #40
- Fixed a lot of reconnect bugs, including #105, #114 and #146, but also multiple ones that weren’t even tracked yet
- Fixed a bug where, upon joining a new channel, the client would show a random other channel instead.
It seems the drawer state is now handled partly by MainActivity like here and other places using the manager abstraction. Maybe this should be unified so all drawer handing happens the same place, like in the manager?