Was tithing 10% required or encouraged by the early church? I cannot find in the New Testament an obligation on Christians to tithe 10% of their income. Instead I read that it is up the individual to decide:


  2 Corinthians 9:7 (NIV1984)
  Each man should give what he has decided in his heart to give, not reluctantly or under compulsion, for God loves a cheerful giver.


Is there a church tradition established by the early church to encourage everyone to tithe 10%?  What was the early church's view on tithing?
The word tithe itself comes from the Old English teogoþa, meaning "tenth" - so technically, tithing is the giving of a tenth by definition. But of course that's not what you're asking!

The idea of giving a tenth comes from the Old Testament:

Leviticus 27:30-33 (MSG):


  "A tenth of the land's produce, whether grain from the ground or fruit
  from the trees, is God's. It is holy to God. If a man buys back any of
  the tenth he has given, he must add twenty percent to it. A tenth of
  the entire herd and flock, every tenth animal that passes under the
  shepherd's rod, is holy to God. He is not permitted to pick out the
  good from the bad or make a substitution. If he dishonestly makes a
  substitution, both animals, the original and the substitute, become
  the possession of the Sanctuary and cannot be redeemed."


Deuteronomy 14:22-29:


  Make an offering of ten percent, a tithe, of all the produce
  which grows in your fields year after year. Bring this into the
  Presence of God, your God, at the place he designates for worship and
  there eat the tithe from your grain, wine, and oil and the firstborn
  from your herds and flocks. In this way you will learn to live in deep
  reverence before God, your God, as long as you live. But if the place
  God, your God, designates for worship is too far away and you can't
  carry your tithe that far, God, your God, will still bless you:
  exchange your tithe for money and take the money to the place God,
  your God, has chosen to be worshiped. Use the money to buy anything
  you want: cattle, sheep, wine, or beer—anything that looks good to
  you. You and your family can then feast in the Presence of God, your
  God, and have a good time.
  
  Meanwhile, don't forget to take good care of the Levites who live
  in your towns; they won't get any property or inheritance of their own
  as you will.
  
  At the end of every third year, gather the tithe from all your
  produce of that year and put it aside in storage. Keep it in reserve
  for the Levite who won't get any property or inheritance as you will,
  and for the foreigner, the orphan, and the widow who live in your
  neighborhood. That way they'll have plenty to eat and God, your God,
  will bless you in all your work.


But, as you rightly say, in the New Testament we are instructed to give what we can, or to give whatever we feel is the right amount. Working out what that right amount is, is of course different for each person and therefore many have sought guidance on what the correct amount should be.

The passages in Leviticus and Deuteronomy don't just give an instruction but give some reasoning too; by giving ten per cent of everything in worship to God, we still have enough left over to live comfortably on.

When we look at Jesus' teaching on giving, he calls us to give much more than 10 per cent:

Matthew 19:21 (MSG)


  "If you want to give it all you've got," Jesus replied, "go sell your
  possessions; give everything to the poor. All your wealth will then be
  in heaven. Then come follow me."


Mark 12:40-42 (MSG)


  Sitting across from the offering box, he was observing how the crowd
  tossed money in for the collection. Many of the rich were making large
  contributions. One poor widow came up and put in two small coins—a
  measly two cents. Jesus called his disciples over and said, "The truth
  is that this poor widow gave more to the collection than all the
  others put together. All the others gave what they'll never miss; she
  gave extravagantly what she couldn't afford—she gave her all."


On that basis, we might view ten per cent as the minimum we should be giving. The church I attend (a "New Church") teaches that we should give what we feel is the right amount, 2 Corinthians 9:7 indicates - but as a guideline 10% should be a starting point. (My church also practices what it preaches - 30% of income is given away to other projects and charities).