Backporting doctrine#3084 into 2.7

This release fixes unintentional BC breaks:

1. It was impossible to use deprecated fetch modes with PDO-based drivers.
2. An unsupported option passed to the `Column` object prevented subsequent options from being applied.
3. Date interval values stored prior to upgrade to `v2.7.0` were reported as invalid.

Total issues resolved: **10**

**Backwards Compatibility Fixes:**

- [3082: Custom PDO fetch modes and 2.7.0](doctrine#3082) thanks to @corphi
- [3088: Fix doctrine#3082: Add BC for PDO-only fetch modes](doctrine#3088) thanks to @corphi
- [3089: Don't skip column options.](doctrine#3089) thanks to @andytruong
- [3093: When updating to version v2.7 type DateInterval throws errors](doctrine#3093) thanks to @fnagel
- [3097: Fix compatibility for pre-2.7 DateIntervalType format](doctrine#3097) thanks to @Majkl578

**Documentation Improvements:**

- [3083: Document the correct way of configuring a MariaDB database with serverVersion](doctrine#3083) thanks to @tristanbes
- [3084: README: Add 2.7, drop 2.5](doctrine#3084) thanks to @Majkl578

**Continuous Integration Improvements:**

- [3085: Tests: remove implicit verbose flag](doctrine#3085) thanks to @Majkl578
- [3090: Add symfony tests listener](doctrine#3090) thanks to @greg0ire
- [3095: CI: Add missing listener for MariaDB @ mysqli](doctrine#3095) thanks to @Majkl578

# gpg: directory `/n/.gnupg' created
# gpg: new configuration file `/n/.gnupg/gpg.conf' created
# gpg: WARNING: options in `/n/.gnupg/gpg.conf' are not yet active during this run
# gpg: DBG: locking for `/n/.gnupg/pubring.gpg.lock' done via O_EXCL
# gpg: keyring `/n/.gnupg/pubring.gpg' created
# gpg: Signature made Sun Apr  8 07:24:49 2018     using RSA key ID 543AE995
# gpg: Can't check signature: public key not found

# Conflicts:
#	.gitignore
#	lib/Doctrine/DBAL/Driver/OCI8/Driver.php