moved library into /library, created a new /sample gradle project, support for sending email

+ moved library into `/library`
+ created a new `/sample` gradle project
+ defined `@color/libpastelog_confirmation_background`
+ produces Maven artifacts in `/library/build/mvn-repo`
+ supports sending of email via installed Android email apps
+ touched up strings for ease of indexing in Transifex
+ added copyright where missing
+ updated README
something like that. I just grabbed all this stuff from onPostExecute and threw it into two methods because it needed to be called twice (once more in the case that they click compose email and then back button).

https://github.com/WhisperSystems/libpastelog/blob/master/src/main/java/org/whispersystems/libpastelog/SubmitLogFragment.java#L243