Trim templates before pug compiling (#86)

[aleksejevski]

Fixes #86 .

Changes proposed in this pull request:

• Trim templates code before pug-template compiling, so that the compiler works correctly however many indent before the first letter of the very first line.

/ping @znck

[HerringtonDarkholme]

Just some pedantic comment. Since it only trims the leading space, I wonder if it works for multiple root(used with if) pug file. Like

<template>
  div(v-if="true")
    p some text
  span(v-else)
    span otherwise
</template>

This will be trimmed to

div(v-if="true")
    p some text
  span(v-else)
    span otherwise

Which seems wrong.

[znck]

I had this concern. I tried updating the test case (^^Not a pug user).

I think deindent would be better.

@HerringtonDarkholme Could you add a failing test case?