Fix incorrect schema definition for price

[unfunco]

Fixes an incorrect schema definition for pricing, before this change
the structured data testing tool provided by Google flags the price
as a warning since it contains the currency symbol, a separate
itemprop exists for the priceCurrency, I have added a separate meta
tag for the price without the currenccy symbol.

[okorshenko]

@unfunco Thank you for your contribution!
@avoelkl thank you for processing this PR!

[woosley-mg]

Love this! Thanks @avoelkl

[Amex68]

I was wondering why this fix does not automatically round up the final price in itemprop="price" like magento does?
structured-data test gives this result.
price 185.130001
priceCurrency EUR

Do you have a solution to this issue?

[Ctucker9233]

Still not included in 2.1.10

[avoelkl]

Feel free to open a github issue or create a PR for this @Amex68 @Ctucker9233 (just one issue, please ;) ). Thanks!

[Amex68]

<meta itemprop="price" content="<?php /* @escapeNotVerified */ echo number_format($block->getDisplayValue(), 2, '.', ','); ?>" />

i found a temporary solution to my problem by adding number_format() function to meta price itemprop. :)