secret-handshake: add hint to @Ignore annotations

difference-of-squares: add hint to @Ignore annotation

space-age: add hint to @Ignore annotations

gigasecond: add hint to @Ignore annotations

pangram: add hint to @Ignore annotations

saddle-points: add hint to @Ignore annotations per #440

perfect-numbers: add hint to @Ignore annotations per #444

ref #448

Ref. #448

Ref. #448

Fixes: #440

Fixes: #444

triangle: fix mistake in test name

Fixes: #419

all-your-base: add hint to @Ignore annotations

allergies: add hint to @Ignore annotations

anagram: add hint to @Ignore annotations

acronym: add hint to @Ignore annotations

accumulate: add hint to @Ignore annotations

isogram: rate difficulty 4, reposition

isogram: fix build issues

The test file was trying to import the example code which it shouldn't
do. Also removed unneeded package declarations and renamed the test
file to be consistent.

saddle-points: add to track

rna-transcription: add hint to Ignore annotation

Fixes #420

Base patched Trackler gem off actual version tag.

- was: hand-rolling a version of Trackler based of master and then
  applying changes from the PR/commit/local change to that trackler gem.
- now: using the exact tagged version of Trackler as the basis for the
  hand-rolled gem.

This fixes the issue where a change make to Trackler's master is
incompatible with the current version of x-api.  In short, we were
building the Trackler gem wrong.

nth-prime: simplify example implementation

Secret-handshake: remove whitespace

difference-of-squares: remove whitespace

pascals-triangle: update to v1.0.0 tests

Add script to prune extraneous .keep files

Initial configuration specifies that "first-timers only" issues should
be exempt from cleanup.

palindrome-products: make class use instance methods [Fix #377]