Implement exercises

- [x] acronym
- [ ] affine-cipher
- [ ] all-your-base
- [x] allergies
- [ ] alphametics
- [x] anagram
- [x] armstrong-numbers
- [x] atbash-cipher
- [x] baffling-birthdays
- [ ] bank-account
- [x] binary-search
- [ ] binary-search-tree
- [x] bob
- [ ] book-store
- [x] bottle-song
- [ ] bowling
- [ ] camicia
- [ ] change
- [x] circular-buffer
- [ ] clock
- [x] collatz-conjecture
- [ ] complex-numbers
- [ ] connect
- [ ] crypto-square
- [ ] custom-set
- [x] darts
- [ ] diamond
- [x] difference-of-squares
- [ ] dnd-character
- [ ] dominoes
- [ ] dot-dsl
- [x] eliuds-eggs
- [ ] error-handling
- [ ] etl
- [ ] flatten-array
- [ ] flower-field
- [x] food-chain
- [ ] forth
- [ ] game-of-life
- [ ] gigasecond
- [ ] go-counting
- [ ] grade-school
- [ ] grains
- [ ] grep
- [x] hamming
- [ ] hangman
- [x] hello-world
- [ ] high-scores
- [x] house
- [ ] intergalactic-transmission
- [x] isbn-verifier
- [x] isogram
- [ ] killer-sudoku-helper
- [ ] kindergarten-garden
- [ ] knapsack
- [ ] largest-series-product
- [x] leap
- [ ] ledger
- [ ] lens-person
- [x] line-up
- [ ] linked-list
- [ ] list-ops
- [x] luhn
- [ ] markdown
- [ ] matching-brackets
- [ ] matrix
- [ ] meetup
- [ ] micro-blog
- [ ] nth-prime
- [x] nucleotide-count
- [ ] ocr-numbers
- [ ] paasio
- [ ] palindrome-products
- [x] pangram
- [ ] parallel-letter-frequency
- [ ] pascals-triangle
- [x] perfect-numbers
- [ ] phone-number
- [ ] piecing-it-together
- [ ] pig-latin
- [ ] poker
- [ ] pov
- [ ] prime-factors
- [ ] prism
- [x] protein-translation
- [x] proverb
- [ ] pythagorean-triplet
- [ ] queen-attack
- [ ] rail-fence-cipher
- [x] raindrops
- [ ] rational-numbers
- [ ] react
- [ ] rectangles
- [ ] relative-distance
- [x] resistor-color
- [x] resistor-color-duo
- [x] resistor-color-trio
- [ ] rest-api
- [x] reverse-string
- [x] rna-transcription
- [ ] robot-name
- [x] robot-simulator
- [x] roman-numerals
- [x] rotational-cipher
- [x] run-length-encoding
- [ ] saddle-points
- [ ] satellite
- [ ] say
- [x] scrabble-score
- [x] secret-handshake
- [x] series
- [ ] sgf-parsing
- [x] sieve
- [ ] simple-cipher
- [ ] simple-linked-list
- [x] space-age
- [ ] spiral-matrix
- [ ] split-second-stopwatch
- [x] square-root
- [ ] state-of-tic-tac-toe
- [ ] strain
- [ ] sublist
- [x] sum-of-multiples
- [ ] swift-scheduling
- [ ] tournament
- [ ] transpose
- [ ] tree-building
- [x] triangle
- [x] twelve-days
- [ ] two-bucket
- [x] two-fer
- [ ] variable-length-quantity
- [ ] word-count
- [ ] word-search
- [ ] wordy
- [ ] yacht
- [ ] zebra-puzzle
- [ ] zipper

@vaeng we can use this issue to state which exercises we're working on.