Improve IteratedS2K performance by using a repeated array and feeding block-size input to the hash. Technique from https://code.google.com/p/end-to-end/issues/detail?id=113

The relevant tests now take approximately half as long.

After e2e hash inst_ object is created, set the blockSize.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71873132
Ciphermode CTR
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71885027
IteratedS2k performance: Align initial hash input when there are prepended zeros. This reduces the execution time by approximately 7% for a typical case such as requesting 40 bytes using sha1.

Change from counting up with i to counting down with remaining. This allows us to change this line:
var size = (block_size < count) ? block_size : count;
Which isn't actually what we want, because count is how many passphrase input bytes we want.
The new line is this which seems less prone to bugs:
var size = (block_size < remaining) ? block_size : remaining;
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71926909
Merge branch 'master' of https://code.google.com/p/end-to-end into s2k-sha256

Conflicts:
	javascript/crypto/e2e/openpgp/s2k.js