Remove current_adapter? from test_sanitize_sql_hash_handles_associations

Because of each adapter implementation differences,
`expected_value` string needed to be handled by each adapter.
This commit removes current_adapter
by using ActiveRecord::ConnectionAdapters::Quoting methods.
dependency ActiveSupport::Deprecation
Merge pull request #10519 from eiel/dependency-core_ext-hash-diff

dependency ActiveSupport::Deprecation
Use ruby's Encoding support for tidy_bytes

The previous implementation was quite slow. This leverages some of the
transcoding abilities built into Ruby 1.9 instead. It is roughly 96%
faster.

The roundtrip through UTF_8_MAC here is because ruby won't let you
transcode from UTF_8 to UTF_8. I chose the closest encoding I could
find as an intermediate.
adding test to demonstrate inconsistencies in the AS::Callbacks api
refactor tests for more points
adding more tests around callback inconsistencies
Merge pull request #10521 from yahonda/sanitize_oracle

Remove current_adapter? from test_sanitize_sql_hash_handles_associations
Merge pull request #10355 from burke/master

Use Ruby's native Encoding functionality to implement `tidy_bytes`
we need to indicate the type of callback
Using define method instead of class eval when defining model callbacks.
Based on my benchmark results, this change improves performance
substantially when defining callbacks.

This benchmark (https://gist.github.com/wangjohn/5542610) was run using
the current master and also using my experimental branch which replaced
class_eval with define_single_method.

Using class_eval (current master):

                    user     system      total        real
10 trials       0.000000   0.000000   0.000000 (  0.001568)
50 trials       0.020000   0.000000   0.020000 (  0.021715)
500 trials      0.110000   0.000000   0.110000 (  0.115357)
1000 trials     0.250000   0.000000   0.250000 (  0.260025)
10000 trials    2.560000   0.000000   2.560000 (  2.568408)
50000 trials   12.800000   0.010000  12.810000 ( 12.886871)

Using define_single_method (experimental branch):

                    user     system      total        real
10 trials       0.000000   0.000000   0.000000 (  0.000790)
50 trials       0.000000   0.000000   0.000000 (  0.002960)
500 trials      0.050000   0.010000   0.060000 (  0.055690)
1000 trials     0.100000   0.000000   0.100000 (  0.094073)
10000 trials    0.890000   0.000000   0.890000 (  0.900364)
50000 trials    4.650000   0.000000   4.650000 (  4.686127)