Add open api for account info.

[Argeric]

Add account information API which returns the statistical information of the files uploaded by the user and the balance of layer1.

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This change is 

[boqiu]

Reviewed 8 of 8 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @Argeric)

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api/account_api.go line 43 at r1 (raw file):

	if accountInfo.TxCount > 0 {
		accountInfo.TxTab = 1

Why not return count info directly?

[Argeric]

Reviewed 8 of 8 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @Argeric)

api/account_api.go line 43 at r1 (raw file):

	if accountInfo.TxCount > 0 {
		accountInfo.TxTab = 1

Why not return count info directly?

Fixed. Return count info instead of display flag.

[boqiu]

Reviewed 2 of 2 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @Argeric)