0.3.0:
 * Added custom words list to snowball filter [@sbeckeriv]
 * Fixed problem about initialization: https://github.com/brenes/stopwords-filter/issues/3 [@zackxu1]
0.2.0:
 * Added stopword? method [@s2gatev]
 * Added Sieve class [@s2gatev]
 * Added bulgarian language [@s2gatev]
0.1.0
 * Added simple filter [@brenes]
 * Added snowball filter [@brenes]
