android: added development readme
notification: make icon visible

The previous notification icon was a black exclamation point, which at
least on modern versions of Android is invisible.  Following the
iconography guidelines [1] and using the android-ui-utils notification
icon generator [2] I've made a simple clock icon that in addition to
being visible should also fit in reasonably well with other icons.

I added the Inkscape svg I used to create the icon to a new misc/ folder
because I wasn't sure where else would be good.

 [1] http://developer.android.com/design/style/iconography.html
 [2] http://android-ui-utils.googlecode.com/hg/asset-studio/dist/icons-notification.html
preferences: make gap time configurable

Instead of using a constant 45min gap, put it in the preferences.

This still needs some work: the change in gap time isn't reflected
immediately, only after the next ping fires.
Merge pull request #27 from jeffkaufman/new-ping-icon

notification: make icon visible
pytagtime added default for exclude-weekdays
pytagtime: plot spacing
pytagtime: fix day-of-the-week labels
pytagtime: add a exclude-tags option
pytagtime: make trends and hour-of-the-week plot more useful/pretty
pytagtime: PEP8
pytagtime: anchor day of the week on monday
pytagtime: add obfuscation option for demonstration purposes
pytagtime: optionally show current day/time in plot
pytagtime: option to selecy specific week days (as opposed to excluding them)
pytagtime: improve handling of display of 'current' time/day
pytagtime: add virtual, weighted observations to smooth plots
pytagtime: fix legend coloring, tag selection and mean-after-resampling
pytagtime: add different ways to deal with multiple tags: first, split, double
pytagtime: FIX obfuscation and day-of-the-week plots
pytagtime: Fix error when extra_tags not used