Americanize spellings
further typo correction

@jburel helped me to find these issues
    yet more typo correction

    @jburel helped me to find these issues
further typos/spellings

mostly suggested by @jburel and @hflynn
extra "although" for @hflynn
fix "customise"
Merge pull request #406 from mtbc/americanize-spellings-dev

Americanize spellings, fix typos, expand contractions (rebased)