Signal strength: add more checks to signal strength,

so it doesn't fall under the range of poor signal and automatically
assumes a gsm signal, actually checks if all values are true and not
valid then pass it on to lte or gsm. This fixes cases when gsm signal
is not valid and lte is active. When lte is active and shows a really
weak and gsm signal is not avalible due some broken vendor ril or
just running cdma lte and a few others senario creates this issue.

Change-Id: Ifbc1c65aa62fe62752a03bb5b76c8a23962d0c91
Use a content observer for getting the default APN

Instead of executing a query of the database for the
default APN on every network state change, an observer
is used on the database to be notifited when the apn
has changed. This prevents unneccesary queries on the
the database.

CRs-fixed: 662137

Change-Id: I3155bd8b53a1877413ed54a861df1bfb1853b9e4
Missing break in switch statement

Change-Id: I462c0c5fec96a850032266b04419ec409ad02174
Prevent Showing the Crash Dialog for System UI

After system ui crashes, the crash dialog can prevent the keyguard from
showing if the screen was shut off before the dialog was dismissed. The
user can't recover from this without waiting for the dialog to time out
which takes several minutes.

Not showing the dialog for system ui is a safe way of preventing this
from occuring.

Change-Id: Iac235f3af244f735ef0e043098ed84874e3a84f9
Fix NullPointerException in ListView

There is a NullPointerException in `handleHorizontalFocusWithinListItem()`
because `selectedView.findFocus()` returns null and then there is no null
check when when the assigned variable `currentFocus` is used, although
`View.findFocus()` states that it may return null.

Change-Id: I6897027e9a2a238d9283e6b9f5146198989fcac0
Heads up: Update snooze drawable:

- Use a flat background, icon and "text"
- Use the background color from notifications for the snooze background, too,
  (especially the pressed background, no big difference for normal background)
- Make the drawables larger,
  (in my opinion the drawables are a bit to small, so use a smaller transparent "border")

Conflicts:
	packages/SystemUI/res/drawable-hdpi/ic_heads_up_snooze.png
	packages/SystemUI/res/drawable-hdpi/ic_heads_up_snooze_pressed.png
	packages/SystemUI/res/drawable-mdpi/ic_heads_up_snooze.png
	packages/SystemUI/res/drawable-mdpi/ic_heads_up_snooze_pressed.png
	packages/SystemUI/res/drawable-xhdpi/ic_heads_up_snooze.png
	packages/SystemUI/res/drawable-xhdpi/ic_heads_up_snooze_pressed.png
	packages/SystemUI/res/drawable-xxhdpi/ic_heads_up_snooze.png
	packages/SystemUI/res/drawable-xxhdpi/ic_heads_up_snooze_pressed.png

Change-Id: I5a6521ae82c7db8a392af9d3b2d1767587352024