Allow some or all of the event properties to be empty.

Added a check for null references which occur if a certain event property is not
set. (That previously resulted in a NullPointerException.)

Signed-off-by: Daniele Gobbetti <daniele+git@gobbetti.name>
Move MainActivity.java into correct directory.

Moved MainActivity.java into the directory that corresponds to its package.

Signed-off-by: Daniele Gobbetti <daniele+git@gobbetti.name>
Enter all entries, not only the first one.

Signed-off-by: Daniele Gobbetti <daniele+git@gobbetti.name>
fixed issue 1
Version bump and readme updated.