Parser

[wandersonwhcr]

According issue #6, create a parser that receives as input an array of grammar tokens and outputs an integer representing roman numerals. The tokens will be the output of lexer tokenize method, created at issue #7, but it must not have lexer as dependency.

Also, the parser will be responsible to validate tokens, checking decrescent order. If tokens are not in decrescent order, the parse method must throw an ParserException. Throw this exception if method receive an unknown token, too.

Below, there's a table with tokens and corresponding values.

Token	Value
I	1
IV	4
V	5
IX	9
X	10
XL	40
L	50
XC	90
C	100
CD	400
D	500
CM	900
M	1000