Added Symfony console commands

Added symfony console commands:

get [<key>]: Gets the entry for the specified key or all entries with keys if no key is specified
delete <key>: Deletes the entry from the cache pool with the specified key
set <key> <value>: Adds a new entry to the cache pool or overwrites it if it exists
keys: Gets the currently existing keys in the cache

Example:

./phpCache.php set test test
./phpCache.php set test1 test1
./phpCache.php get

Will output:

+-------+-------+
| KEY   | VALUE |
+-------+-------+
| test  | test  |
| test1 | test1 |
+-------+-------+

./phpCache.php get test

Will output:

+------+-------+
| KEY  | VALUE |
+------+-------+
| test | test  |
+------+-------+

./phpCache.php keys

Will output:

+-------+
| KEYS  |
+-------+
| test  |
| test1 |
+-------+