PROC-118: Expose exception message to ant via BuildException
PROC-114: PROC-55: More consistency around how the builder interprets
rules. Both Allocation and top-level rules can
optionally contain "${ ... }". The generated JSON from the builder
will always contain rules surrounded by curly braces.

Trim whitespace around rules during building.
Better enforcement allocation rules: new check ensuring that rules for
all but the last allocation are non-empty. The rule of the last
allocation should be empty.
PROC-114: PROC-55: garbage-free implementation of removeElExpressionBraces