Support for lex file and output path

Seperated the Gulp options from the Jison options to add support for
reading a lex file and defining the output path in case the input name
doesn't match.

Now the grammar is properly constructed so that Jison is capable of
parsing tokens and generate a working parser and lexer with it.

**Options changed**
- lexFile: input path to a lex file, ie `tokens.jisonlex`
- outFile: output path of the result
- jisonOptions: options passed to `Jison`

**Note**
*Creation of the grammar is identical with the cli version of Jison.*