update to spring boot 1.1.5, vaadin 7.2.6, gradle wrapper 1.12
indy no longer seems to work and crashes hard with some AST traces
also use a variable for the vaadin4spring version; make vaadin 7.3.0.rc1 the vaadin version
make valo the default theme
added gradlew
added spock
use gradle 2.0
some comments and indenting around the gradle-vaadin-plugin code