[AdBlock] Improved performance of loading rules

Don't use regexps for parsing rules.
Added benchmark for loading subscriptions

Before:

********* Start testing of AdBlockParseRule *********
Config: Using QTest library 4.8.6, Qt 4.8.6
PASS   : AdBlockParseRule::initTestCase()
RESULT : AdBlockParseRule::parseEasyList():
     596.3 msecs per iteration (total: 2,982, iterations: 5)
PASS   : AdBlockParseRule::parseEasyList()
PASS   : AdBlockParseRule::cleanupTestCase()
Totals: 3 passed, 0 failed, 0 skipped
********* Finished testing of AdBlockParseRule *********

After:

********* Start testing of AdBlockParseRule *********
Config: Using QTest library 4.8.6, Qt 4.8.6
PASS   : AdBlockParseRule::initTestCase()
RESULT : AdBlockParseRule::parseEasyList():
     481.8 msecs per iteration (total: 2,409, iterations: 5)
PASS   : AdBlockParseRule::parseEasyList()
PASS   : AdBlockParseRule::cleanupTestCase()
Totals: 3 passed, 0 failed, 0 skipped
********* Finished testing of AdBlockParseRule *********